Domino Specialty Ingredients
For information on any cane-sugar based functional ingredient, Domino Specialty Ingredients is a food formulator’s best friend. From making brown sugar flowable and easier to handle, to taking the stickiness out of honey, to adding sheen to donut glazes, Domino Specialty Ingredients provides the products, technology and support–all with the click of a mouse.
Plant extracts outperform chemical additives as preservatives for processed meat
The grape seed and pine bark extracts also reduced measures of oxidation and therefore meat spoilage after nine days, whereas the synthetically treated meat showed a more than 200 percent increase in oxidation.
“Results of this work show that ActiVin and Pycnogenol are promising additives for maintaining the quality and safety of cooked beef,” said the researchers.
In addition to replacing harmful synthetic preservatives, natural preservatives have the added advantage of actually boosting health. For example, studies have linked grape seed extracts like ActiVin to improved cardiovascular health through its ability to limit oxidation of LDL (bad) cholesterol, and other studies suggest pine bark may improve conditions such as asthma and male infertility, and has improved memory in laboratory mice.
The color of the meats were also affected by the extracts, as grape seed and pine bark both lightened the color of the meat and increased its redness.
“The retention of the red color of cooked beef treated with ActiVin and Pycnogenol may result from their antioxidative effects and their contribution of pigments. The fact that ground beef treated with ActiVin and Pycnogenol retained more redness during cooking may result in consumers avoiding consumption of undercooked meat,” the study said.
The researchers noted one possible drawback of using the natural extracts in high concentrations: a negative impact on consumers’ perception of taste, color and texture of the meat. The researchers concluded that more research would be needed to see if grape seed and pine bark extracts could be used in high enough concentrations to be effective without impacting flavor and aroma.
Essential oils could replace chemical additives in preserving meat products
The results of my research support the idea that new food ingredients from plant kingdom are of interest for the meat industry,” lead author Mario Estvez. “Using “functional ingredients” such as those containing flavonoids are excellent options to enhance the nutritional and technological properties of a wide range of foods.”In the study, the researchers studied three pates, one with sage and rosemary oils, one with BHA and BHT, and one with no antioxidants, after they had been stored at 39 degrees Fahrenheit for 90 days.
After 30 days, the scientists analyzed the levels of polyunsaturated fatty acids (PUFA), thibarbituric acid reactive substances (TBARS), and lipid-derived volatiles in the pates. The essential oil pate also showed a significantly reduced loss of PUFA levels compared to the synthetically preserved and control pates, and the essential oils also performed better in the inhibition of oxidative deterioration. No difference was observed after 90 days.
“Results from the present study agree with those obtained (previously), denoting even the possibility of replacing synthetic antioxidants such as BHT with natural extracts with antioxidant activity obtained from plants,” wrote the authors in the January issue of LWT - Food Science and Technology (Lebensmittel-Wissenschaft und -Technologie). “Furthermore, the addition of plant essential oils greatly influences the aromatic profile of the products in which they are added since some volatile components of these essential oils are terpenes which might contribute to add specific aromatic notes.”
While the study results suggest that natural alternatives to synthetic preservatives are viable, Estvez said some obstacles still remain.
“Regardless of the costs, the main challenges of using these substances on meat products are related to consumer’s acceptability,” he said. “It is essential to carry out experimental works to prove the effectiveness of these substances is every single product because their activity as antioxidants depends on a large number of factors, including the characteristics of the food.”
The study comes at a time when plant-based alternatives to chemical preservatives are increasing in popularity, even to the point that the synthetic antioxidant market is in decline while the natural antioxidant market is growing, according to a 2003 report by Frost and Sullivan.
Organic food market expected to surge over next five years as consumers demand chemical-free food
As more consumers vote for chemical-free food through their spending, the U.S. organic market is set to grow strongly in the next five years, according to consumer media and market research organization Mintel.The report states that the increased availability of organic foods in mainstream grocery stores is going to significantly affect which foods consumers purchase, and valued the organic food market at about $3.6 billion in 2006, up $2.1 billion dollars since 2001. The researchers estimate that the market will grow a further 44 percent between 2006 and 2011, as organic food sales through food, drug and mass merchandisers (FDM) have already jumped 38 percent between 2004 and 2006, spurred on by increasing demand for organic fruits, vegetables and prepared foods. The organic meat portion of the market is also set to grow significantly, the report found, as sales increased 140 percent between 2004 and 2006.
The report cites consumer desire to avoid pesticides, hormones, antibiotics, chemicals, genetically modified organisms, and bovine spongiform encephalitis (BSE, also known as mad cow disease) as the major force behind the organic market’s growth.
Retailers are attempting to capitalize on the increased interest in organic foods by offering private label organic products at competitive prices; the report found that price was a major barrier for consumers who have not yet purchased organic products. Currently, about 65 percent of Mintel’s respondents said they purchase their organic foods through supermarkets, 45 percent said they buy from health food stores, and 24 percent named Wal-Mart as their organic food source. Mintel said that Wal-Mart’s planned organic foods line — which will be available at a relatively cheap 10 percent price increase over conventional products — will boost the market overall.
However, Mintel’s report found that consumers were not just looking for their labels to say “organic,” and most were looking for products free from artificial ingredients and additives. Supermarkets have been trying to tempt consumers through “natural” ingredients, which can use mainstream (as opposed to organic) ingredients as long as they are not artificial ingredients, but natural labeling is not consistent, nor is it controlled by the government.
“Consumers are rapidly becoming aware of the dangers of non-organic foods,” said Mike Adams, author of Grocery Warning, a book that details dangerous ingredients in everyday foods. “The more people learn about the chemicals, additives and contaminants found in non-organic foods, the greater their demand for organic. It’s only natural to see this demand surge as consumers are increasingly learning the truth about the foods found in grocery stores.”
When Mintel published its report, spokespersons were quick to point out that they could not estimate the impact of the recent E. coli outbreak in fresh cut spinach.
Lubricant Additives are safe for incidental food contact
With ability to handle temperature extremes, high loading, and high speeds, 4300FG series of lubricant additives complies with CFR 21 Section 178.3570 guidelines for NSF HX-1 registration. Components include tackifier and thickener, antioxidants, and corrosion inhibitors. Allowing lube manufacturer to develop products for diverse applications, additive packages are designed to be used in technical white mineral oils, polyalphaolefins, or vegetable oils.
Designed for incidental food contact, Lubrizol’s 4300FG series consists of components, additive packages and blended fluids that provide maximum flexibility for lube marketers and comply with CFR 21 Section 178.3570 guidelines necessary for NSF HX-1 registration.
Components include a tackifier and a thickener, antioxidants and corrosion inhibitors. Additive packages are designed to enable the lube manufacturer to develop products for diverse applications such as hydraulic oils, gear oils, worm gear oils, chain oils, etc. Lubrizol technology will allow the handling of temperature extremes, high loading and high speeds. These packages may be used in technical white mineral oils, polyalphaolefins (PAO) or vegetable oils, offering the formulator maximum flexibility. Incidental food contact lubricants require special handling and use of approved raw materials that can add cost and complexity to an operation. The blended fluids are available for private labeling to address this issue.
The Lubrizol Corporation (NYSE: LZ) is an innovative specialty chemical company that produces and supplies technologies that improve the quality and performance of our customers’ products in the global transportation, industrial and consumer markets. These technologies include lubricant additives for engine oils, other transportation-related fluids and industrial lubricants, as well as fuel additives for gasoline and diesel fuel. In addition, Lubrizol makes ingredients and additives for personal care products and pharmaceuticals; specialty materials, including plastics technology and performance coatings in the form of specialty resins and additives. Lubrizol’s industry-leading technologies in additives, ingredients and compounds enhance the quality, performance and value of customers’ products, while reducing their environmental impact.
With headquarters in Wickliffe, Ohio, The Lubrizol Corporation, a Fortune 500 company, owns and operates manufacturing facilities in 20 countries, as well as sales and technical offices around the world. Founded in 1928, Lubrizol has approximately 6,900 employees worldwide. Revenues for 2005 were $3.6 billion, excluding operations discontinued in 2006 that had 2005 revenues of $0.4 billion. For more information, visit www.lubrizol.com.
Additives in polymers; industrial analysis and applications
Additives in polymers; industrial analysis and applications.
Bart, Jan C.J.
John Wiley & Sons
2005
819 pages
$335.00
Hardcover
TP1142
Bart (industrial chemistry, University of Messina) examines the latest instrumental methods for monitoring, deformulation, and troubleshooting in industrial analysis and applications of additives in polymers. Current analytical strategy and best practices in the field are outlined and illustrated with industrial applications and case studies. Coverage encompasses areas including sample preparation, separation, identification, hyphenation and quantification techniques, microstructural analysis, additive dynamics, and in-process analysis. The book is for analytical chemists, polymer and material scientists, advanced students, lab technicians, and other practitioners working for industry, academia, government, and regulatory agencies concerned with plastic products.
Marketing Authorisation: Distinction Between Food Additives and Medicinal Products
The case HLH Warenvertriebs GmbH and another v Germany (Joined cases C-211/03, C-299/03 and C-316/03 to C-318/03) was decided by the Court of Justice of the European Communities (First Chamber).
The applicants, HLH Warenvertriebs GmbH and another, intended to import into Germany and market certain products that were on the market as food supplements in the Netherlands. They planned to market the products also as food supplements. The applicant applied for marketing authorisation to market the products in Germany as food supplements. The applicants requested the German federal ministry for consumer protection, food and agriculture to adopt a general decision concerning marketing authorisations, pursuant to national law. The German Federal Ministry refused and they brought proceedings before the regional administrative court against this refusal. The court dismissed their actions. The main ground on which the proceedings were dismissed was that the products were medicinal products, not foodstuffs.
The applicants appealed to the higher administrative court. This court then stayed proceedings and referred the case to the Court of Justice of the European Communities (”European Court”) for a preliminary ruling regarding the interpretation of a number of provisions of Community law, in particular:-
Novel foods and novel food ingredients (Parliament and Council Regulation (EC) 258/97);
Articles 28 and 30 of the EC Treaty;
The Community code relating to medicinal products for human use (Parliament and Council Directive (EC) 2001/83);
The general principles and requirements of food law, establishing the European Food Safety Authority and laying down procedures in matters of food safety (Parliament and Council Regulation (EC) 178/2002); and The approximation of the laws of the member states relating to food supplements (Parliament and Council Directive (EC) 2002/46).
The European Court decided:
In order to classify a product as a medicinal product or as a foodstuff, all the characteristics of the product had to be taken into account as established in the initial stage of the product i.e. where it was mixed, the method by which it was used and whether with water or with yoghurt.
Regulation 178/2002 (No 4 above) constituted an additional set of rules in relation to Council Directive (EC) 2002/46 (No 5 above).
It was only the provisions of Community law specific to medicinal products which applied to a product that satisfied equally the conditions for classification as a foodstuff and the conditions for classification as a medicinal product.
The competent authorities in member states had to:-
use the pharmacological properties of a product to ascertain, in the light of the potential capacities of the product, whether it might, for the purposes of the second subparagraph of art 1(2) of directive 2001/83 (No 3 above), be administered to human beings with a view to making a medical diagnosis or to restoring, correcting or modifying physiological functions in human beings.
establish the risk to health of human beings of using this product in the context of the classification of the product as a medicinal product.
A product which constituted a medicinal product within the meaning of directive 2001/83 (No 3 above) might be imported into another member state only upon acquisition of a marketing authorisation issued in accordance with the provisions of that directive, even where it was lawfully marketed as a foodstuff in another member state.
The concept of ‘upper safe levels’ in art 5(1)(a) of directive 2002/46 (No 5 above) was not of importance for the purposes of drawing a distinction between medicinal products and foodstuffs.
In evaluating the risks that foodstuffs or food supplements might constitute for human health by a member state, the member state has to take into account whether there is a nutritional need in the population of that member state. However, the absence of such a nutritional need did not in itself justify, either under art 30 EC (No 1 above) or under art 12 of directive 2002/46, a complete ban on marketing foodstuffs or food supplements lawfully manufactured or placed on the market in another member state.
Article 1(2) of regulation 258/97 (No 1 above) should be interpreted to mean that a food or a food ingredient had not been used for human consumption to a significant degree within the Community if, when all the circumstances of the case were taken into account, it was established that that food or food ingredient had not been consumed in a significant quantity by humans in any of the member states before the reference date.
A national court could not directly refer questions regarding the classification of products to the European Food Safety Authority (EFSA). If the EFSA delivered an opinion, say, in a case forming the subject-matter of a dispute pending before a national court, this might constitute evidence that the national court could take into consideration in the context of that dispute.
Do Oil Additives Really Work?
With all of the negative articles about oil additives, which have been written and supported extensively by special interest groups, its time to tell the real truth about oil additives. In most cases they perform a positive function and with regular use can provide a number of benefits to vehicles and equipment.
First, lets get one thing clear, it’s important to distinguish from oil additives developed by companies that have been extensively tested, and others, usually made by individuals, without such testing and documentation. Anyone can put an additive package together and have a label made. There are many on the market, which have no real testing, even though, they claim they do. This is where additives have gotten a bad name. On the other hand there are a number of companies that sell additives that have extensive research and development teams that have tested their additive packages. For example, Lubrizol www.lubrizol.com whose revenues were over 4 billion dollars for 2005 specializes in additive packages including aftermarket engine and fuel treatments. Anyone doing this kind of volume is not selling snake oil to millions of dumb consumers—just doesn’t happen. And they are only one of several that are very large. Others include Oronite, Ethyl, Infineum, Bardahl, Wynn’s, SFR, Power Up, STP, Slick 50. This is just a partial list of companies that have well documented additive products.
In actuality additives are used in most all lubricants, because even the best synthetic base oils cannot protect vital parts alone, as it’s the additives that do all of the work. Let’s concentrate on the internal combustion engine in looking at the need for additives. According to the American Petroleum Institute the powerful watchdog for the oil companies, “The temperatures and types of service under which an engine is operated vary markedly. Moderate-speed driving on short trips or stop-and-go driving in traffic uses only a fraction of the available engine power. Because the cooling systems must be capable of meeting the cooling requirements of the engine at high speeds, they may overcool the engine in short-trip driving. In such light-duty service engines and motor oils warm up slowly and often do not reach proper operating temperatures.
Under these conditions automatic chokes will provide the engine with the rich air-fuel mixture it needs to operate smoothly at cold temperatures, but this richness will result in incomplete combustion. Soot and partially oxidized hydrocarbons undergo further oxidation in the crankcase, forming sludge and varnish deposits. These may clog oil screens or plug oil rings, interfering with oil circulation and control, or they may cause hydraulic valve lifters and valves to stick. Corrosive acids are formed that cause wear on piston rings, cylinders, and occasionally on piston skirts. Steam from combustion condenses on cylinder walls and drains into the crankcase. Water, often in combination with acidic gases, may cause valve lifters to rust and stick. It may also create rust deposits on piston pins, rocker arm shafts, and valve stems. Liquid fuel leaking past the piston rings dilutes the oil and reduces its lubricating value. These are some of the effects of engine operation at cold temperatures.
In contrast legal speed limit driving and long trips allow the engine and oil to warm p properly. The choke is open, and the carburetor is feeding the cylinders with a lean, clean burning air-fuel mixture. As a result there little or no incomplete combustion to produce soot other residue. Under these conditions water compensation is not a problem, nor is dilution of the motor oil by raw fuel.” Additives have been developed to address these problems as most of us qualify much of time for driving in severe service conditions. Furthermore, the API goes on to say “Under some conditions it is impossible to maintain a continuous oil film between moving parts, and there is intermittent metal-to-metal contact between the high spots on sliding surfaces. Lubrication engineers call this boundary lubrication. Under these circumstances the load is only partially supported by the oil film. The oil film is ruptured, resulting in significant metal-to-metal contact. When this occurs, the friction generated between the surfaces can produce enough heat to cause on or both of the metals in contact to melt and weld together. Unless counteracted by proper additive treatment, the result is either immediate seizure or the tearing apart and roughening of surfaces.
Boundary lubrication conditions always exist during engine starting and often during the operation of a new or rebuilt engine. Boundary lubrication is also found around the top piston ring where oil supply is limited, temperatures are high, and a reversal of piston motion occurs.
Extreme pressure conditions can develop between heavily loaded parts from lack of lubrication, inadequate clearance, extreme heat, and sometimes as a result of using the wrong type or grade of lubricant for the operating conditions of the engine. Since motor oils do not contain extreme pressure agents this is an area that aftermarket additive manufacturers focus a lot of attention. In modern engines the valve train with its cams, valve lifters, push rods, valve stem tips, and parts of the rocker arms operate under conditions of extreme pressure because they carry heavy loads on very small contact areas. Unit loading, which may be as high as 200,000 pounds per square inch, is many times greater than the loads on the connecting rod bearings or on the piston pins.” Motor oils rarely contain extreme pressure additives, thus premature wear could take place. The preceding has laid the groundwork for the need for additives. Additives to take care of the deposits and sludge, called detergent/dispersant additives, anti-oxidants to delay the effects of oxidation. Anti-foaming additives are important as if foaming occurs in a motor oil the film strength is reduced allowing wear. And since base oils alone cannot withstand the metal-to-metal contact inside an engine, anti-wear agents are needed. With acids there is also a need for corrosion inhibitors; and in reducing friction in hydrodynamic lubrication such as on the cylinder liners, where metal-to-metal contact does not occur, friction modifiers or lubricity additives are desired to improve engine efficiency and improve mileage.
If additives are a necessity to reducing wear in an engine and are contained in motor oils, then that must be the end of the story right? Not quite. Few people know that the oil companies do not make the specifications for motor oil. They are required to make their motor oils to meet the Original Equipment Manufacturers (OEM) specifications. Motor oil specifications are established by the International Lubricant Standardization and Approval Committee, which consists of the Big Three domestic car manufacturers as well as the Japanese car manufacturers. ILSAC defines the performance characteristics and the chemistry of the oil it will accept for use in its engines; and then the American Petroleum Institute (API) makes sure the oil sold by marketers displaying that label meets the definition. This isn’t an easy process as the OEM’s are not best of friends as competitors, thus they have driven the cost of this highly political process into the hundreds of millions of dollars. Yes, just to come up with a new specification. ILSAC comes up with a series of Sequence Tests that a motor oil must pass to receive certification. The public is not aware of the fact that, a motor oil formulation going through the process, can fail a Sequence test two times and not have to re-formulate. If the formulation fails three times on a single Sequence test then it must be re-formulated and start over. To control how many additive companies that can supply the complete packages to meet the new warranty specification, ILSAC has proposed the testing process to cost a whopping 1.5 million dollars for diesel motor oil warranty, and over $500,000 for gasoline engine motor oil. That is assuming you pass on the first try other wise the costs can escalate. With specifications changing so fast, only a few large companies can recover their cost of development in such a short time. When oil companies advertise they exceed the highest standard available it’s the only one so it’s also the lowest standard. Regardless of how good your motor oil is there is only one standard, currently GF-4 for gasoline engines and CJ-4 for diesel engines. There is no incentive to improve beyond the lowest passing standard because it costs money to add additives that do the work. Motor oil companies often cut additives to the core to exceed the standard by the narrowest of margins to cut costs and maximize revenues. In summary, the oil companies make their motor oils to the OEM’s standards not theirs!
Two questions are always asked when discussing oil additives and whether they work or not and they are: Why doesn’t the OEM’s recommend oil additives and why doesn’t the oil companies get into the additive business if they are so good.
First, it seems fairly obviously why the OEM’s do not want to recommend oil additives as they have spent millions of dollars protecting their engineering. When I say protecting their engineering I mean using a fluid to insure that the engine, on average, lasts as long as they engineered it to last. They are in the business of selling cars and they know to be competitive it has to last a certain amount of time, but then they want you to purchase a new car. They do not want to have to test other additive products as they have spent money to develop their specification. This does not mean that oil additives can’t be beneficial as a Sequence Wear Test was run by SFR Corporation with the leading selling motor oil in the United States—once without the additive and once with the leading motor oil and 5% SFR’s additive package SFR 100. The test was run by a large testing facility certified to conduct tests for motor oil warranty approval. The results of these expensive tests showed that the additive package reduced the overall wear of the leading motor oil by 17% and on the exhaust lobe part of the test the results were an outstanding 80-90% reduction in wear using the additive. When OEM’s are developing their own specifications they are not going to say their specification needs help in performance by using an additive as it’s against their best interest. However, no OEM will state that the use of an additive in itself will void a warranty. The reason is that they must run the battery of tests which costs from $500,000 to 1, 500,000 per test. This doesn’t mean that an additive could not hurt or destroy an engine and that is why the leading additive suppliers have performed extensive testing to validate their product.
Why aren’t the oil companies involved in the additive market? Truth is they are the leaders in the development of aftermarket oil additives. Many of the additives used in the aftermarket industry are actually purchased from the oil companies. The oil companies, with their big budgets, can provide hundreds of thousands of dollars of testing to validate additive performance. The public is unaware of this though as most all oil companies run their additive divisions as separate companies under their corporate umbrella. They include Infineum for Exxon/Mobil, Oronite for Chevron/Texaco and then there is Ethyl who is well known for its tetraethyl lead previously found in all gasoline. Shell has their own as does Castrol. Quaker State owned Slick 50 additive company, and I cannot see them buying this company if the product would not have any benefit as the liability would be too great if the products would not perform. Chevron sells Techron today an aftermarket gasoline treatment, Valvoline has marketed aftermarket additives as well as others including the additive leader Lubrizol. One must realize the following: The oil companies make products to meet the OEM’s requirements not theirs. You could call an oil company up right now and ask if oil could be made better and your response would be similar to this: We have over 150 chemists in this building alone and if motor oil could be made better, we would be the ones to do it. On the other hand we could call their additive division and say we want a heavy duty performing oil that would out perform the current specification and they could fax you a product with hundreds of thousands of dollars of testing documentation.
It all boils down to special interest groups protecting their special interests. The OEM’s and the major oil companies all protect their interests. It’s hard for an oil company not to defend their oil as the best there is, but in reality we know the specification was created by the OEM. This is the main reason why so many articles have been posted about why additives do not work. A magazine writer doing an article on additives will go to a source that he or she thinks is an expert, and thus they call someone up at the oil company. That person reinforces that their oil is the best and doesn’t need additional additives. Even the specialty motor oil marketers such as Amsoil support the notion that oil additives are not needed. They do not want competition from additive companies because in their mind all you need is their oil. Unfortunately, being a (MLM) multi-level marketing company, most all are part-time, thus more laymen in the business than any other oil marketing company. Their dealers go to great lengths supporting articles that additives do not work. What a paradox, because if additives do not work, than why is their motor oil better than anyone else’s. Doesn’t take much thought to figure that one out.
To support the issue of additives all one has to do is look at Mobil’s new marketing campaign. They still claim their oil meets GF-4 or the new specification that API certifies, but they are now calling for extended drain intervals. And, if you read anything about Mobil’s new products is that it has to do with additional additives being used, mainly detergents. From their literature it states: Mobil Clean 7500 is a synthetic blend formulation with a boosted level of cleaning performance, 18 percent beyond the level of even our premium Mobil Clean 5000 conventional motor oil, to keep your engine cleaner longer.
Additives are what make motor oil what it is and additives are what make aftermarket additive manufacturers their gains in performance. It’s all based on testing both engine and fleet tests. Additives have been around for years and auto parts stores devote entire rows of products related to additives. Additive manufacturers are seen as nuisances because the OEM’s engineer their products to last on average a certain amount of time and the oil companies make their products to meet the OEM’s needs. So if you want to find out about additives you wouldn’t ask the OEM’s or oil companies but the testing laboratories like Southwest Research Institute and Auto Research Laboratories Inc. that performs thousands of tests each year. I am including some links to additive suppliers and testing companies so that you can see the tremendous amount of data that is available from large substantial companies. They include www.lubrizol, www.infineum.com, www.rheinchemie.com, www.sfrcorp.com, www.stp.com, www.rtvanderbilt.com, www.ethyl.com, www.powerup.com, www.slick50.com, www.wynns.com, www.bardahl.com, www.oronite.com and many more that I have not mentioned.
Alumina (Aluminium Oxide) – The Different Types of Commercially Available Grades
Background
Alumina is the most widely used oxide ceramic material. Its applications are widespread, and include spark plugs, tap washers, pump seals, electronic substrates, grinding media, abrasion resistant tiles, cutting tools, bioceramics, (hip-joints), body armour, laboratory ware and wear parts for the textile and paper industries. Very large tonnages are also used in the manufacture of monolithic and brick refractories. It is also used mixed with other materials such as flake graphite where even more severe applications are envisaged, such as pouring spouts and sliding gate valves.
Key Properties
The characteristics which alumina has and which are important for these applications are shown below.
·        High compression strength
·        High hardness
·        Resistant to abrasion
·        Resistant to chemical attack by a wide range of chemicals even at elevated temperatures
·        High thermal conductivity
·        Resistant to thermal shock
·        High degree of refractoriness
·        High dielectric strength
·        High electrical resistivity even at elevated temperatures
·        Transparent to microwave radio frequencies
·        Low neutron cross section capture area
·        Raw material readily available and price not subject to violent fluctuation
Annual Production
Annual production of alumina is some 45 million tonnes, of which 90% is used in the manufacture of aluminium metal by electrolysis.
Where Does Alumina Come From?
Most of the aluminium oxide produced commercially is obtained by the calcination of aluminium hydroxide (frequently termed alumina trihydrate or ATH). The aluminium hydroxide is virtually all made by the Bayer Process. This involves the digestion of bauxite in caustic soda and the subsequent precipitation of aluminium hydroxide by the addition of fine seed crystals of aluminium hydroxide.
Phases of Alumina
Aluminium oxide exists in many forms, a, c, h, d, k, q, g, r; these arise during the heat treatment of aluminium hydroxide or aluminium oxy hydroxide. The most thermodynamically stable form is a-aluminium oxide.
Aluminium Hydroxides
Aluminium forms a range of hydroxides; some of these are well characterised crystalline compounds, whilst others are ill-defined amorphous compounds. The most common trihydroxides are gibbsite, bayerite and nordstrandite, whilst the more common oxide hydroxide forms are boehmite and diaspore.
Commercially the most important form is gibbsite, although bayerite and boehmite are also manufactured on an industrial scale.
Aluminium hydroxide has a wide range of uses, such as flame retardants in plastics and rubber, paper fillers and extenders, toothpaste filler, antacids, titania coating and as a feedstock for the manufacture of aluminium chemicals, e.g. aluminium sulfate, aluminium chlorides, poly aluminium chloride, aluminium nitrate.
Commercial Grades of Alumina
Smelter Grade Alumina
Smelter or metallurgical grade alumina is the name given to alumina utilised in the manufacture of aluminium metal. Historically it was manufactured from aluminium hydroxide using rotary kilns but is now generally produced in fluid bed or fluid flash calciners. In the fluid flash processes the aluminium hydroxide is fed into a counter-current stream of hot air obtained by burning fuel oil or gas. The first effect is that of removing the free water and this is followed by removal of the chemically combined water; this occurs over a range of temperatures between 180-600ºC. The dehydrated alumina is principally in the form of activated alumina and the surface area gradually decreases as the temperature rises towards 1000ºC. Further calcination at temperatures > 1000ºC converts this to the more stable a-form. The conversion to the a-form is typically of the order of 25% and the specific surface area is relatively high at >50m²/g due to the presence of transition aluminas.
Calcined Alumina
If aluminium hydroxide is heated to a temperature in excess of 1100ºC, then it passes through the transition phases of alumina referred to above.
The final product, if a high enough temperature is used, is a-alumina. The manufacturing process is commercially undertaken in long rotary kilns. Mineralisers are frequently added to catalyse the reaction and bring down the temperature at which the a-alumina phase forms; fluoride salts are the most commonly used mineralisers.
These calcined alumina products are used in a wide range of ceramic and refractory applications. The main impurity present is sodium oxide. Various grades are produced which differ in crystallite size, morphology and chemical impurities.
The calcined grades are often sub-divided into ordinary soda, medium soda (soda level 0.15-0.25% wt%) and low soda alumina.
Low Soda Alumina
Many applications, particularly in the electrical/electronic areas, require a low level of soda to be present in the alumina. A low soda alumina is generally defined as an alumina with soda content of <0.1% by weight. This can be manufactured by many different routes including acid washing, chlorine addition, boron addition, and utilisation of soda adsorbing compounds.
Reactive Alumina
“Reactive†alumina is the terms normally given to a relatively high purity and small crystal size (<1 mm) alumina which sinters to a fully dense body at lower temperatures than low soda, medium-soda or ordinary-soda aluminas. These powders are normally supplied after intensive ball-milling which breaks up the agglomerates produced after calcination. They are utilised where exceptional strength, wear resistance, temperature resistance, surface finish or chemical inertness are required.
Tabular Alumina
Tabular alumina is recrystallised or sintered a-alumina, so called because its morphology consists of large, 50-500 mm, flat tablet-shaped crystals of corundum. It is produced by pelletising, extruding, or pressing calcined alumina into shapes and then heating these shapes to a temperature just under their fusion point, 1700-1850ºC in shaft kilns.
After calcination, the spheres of shapes of sintered alumina can be used as they are for some applications, e.g. catalyst beds, or they can be crushed, screened and ground to produce a wide range of sizes. As the material has been sintered it has an especially low porosity, high density, low permeability, good chemical inertness, high refractoriness and is especially suitable for refractory applications.
Fused Alumina
Fused alumina is made in electric arc furnaces by passing a current between vertical carbon electrodes. The heat generated melts the alumina. The furnace consists of a water cooled steel shell and 3-20 tonne batches of material are fused at any one time. The fused alumina has a high density, low porosity, low permeability and high refractoriness. As a result these characteristics, it is used in the manufacture of abrasives and refractories.
High Purity Aluminas
High purity aluminas are normally classified as those with a purity of 99.99% and can be manufactured by routes starting from Bayer hydrate using successive activations and washings, or via a chloride to achieve the necessary degree of purity. Even higher purities are manufactured by calcining ammonium aluminium sulfate or from aluminium metal. In the case of the route via ammonium aluminium sulfate, the necessary degree of purity is obtained by successive recrystallisations. Especially high purities can be made from aluminium by reacting the metal with an alcohol, purifying the aluminium alkoxide by distillation, hydrolysing and the calcination. A minor route involves subjecting super purity aluminium metal pellets under distilled water to a spark discharge.
Applications include the manufacture of synthetic gem stones such as rubies and yttrium aluminium garnets for lasers, and sapphires for instrument windows and lasers.
Adhesives – Modern Types of Adhesives
Background
A bewildering variety of adhesives are available from a range of adhesive manufacturers. However, it is possible to simplify the choice by classifying the adhesive, and this can be done either by the way they are used or by their chemical type. The strongest adhesives solidify by a chemical reaction, Weaker varieties harden by some physical change. The major classifications are described in the following sections.
Anaerobics
Anaerobic adhesives cure when in contact with metal, and the air is excluded, e.g. when a bolt is home in a thread. They are often known as “locking compounds”, being used to secure, seal and retain turned, threaded, or similarly close fitting parts. They are based on synthetic acrylic resins.
Cyanoacrylates
Cyanoacrylate adhesives cure through reaction with moisture held on the surface to be bonded. They need close fitting joints and usually solidify in seconds. Cyanoacrylates are suited to small plastic parts and to rubber. They are a special type of acrylic resin.
Toughened Acrylics
Toughened acrylics are fast curing and offer high strength and toughness. Both one and two part systems are available. In two part systems, no mixing is required because the adhesive is applied to one substrate, the activator to the second substrate, and the substrates joined. They tolerate minimal surface preparation and bond well to a wide range of materials.
Epoxies
Epoxy adhesives consist of an epoxy resin plus a hardener. They allow great versatility in formulation since there are many resins and many different hardeners. Epoxy adhesives can be used to join most materials. These materials have good strength, do not produce volatiles during curing, and have low shrinkage. However, epoxies can have low peel strength and flexibility and can be brittle. Epoxy adhesives are available in one part, two part and film form and produce extremely strong durable bonds with most materials.
Polyurethanes
Polyurethane adhesives are chemically reactive formulations that may be one or two part systems and are usually fast curing. They provide strong resilient joints which are impact resistant and have better low temperature strength than any other adhesive. Polyurethanes are useful for bonding glass fibre reinforced plastics (GRP). The fast cure usually necessitates applying the adhesives by machine. They are often used with primers.
Silicones
Silicones are not very strong adhesives, but are known for their flexibility and high temperature resistance. They are available in single or two part forms. The latter function like the two part epoxies, the former like the single part polyurethanes. When the single part adhesives cure they liberate either alcohol or acetic acid (the familiar smell of vinegar). They are often used as bath and shower sealants. Their adhesion to surfaces is only fair but like their flexibility, their durability is excellent. The two part versions need a hardening agent to be mixed into the resin. Two forms are available, those which liberate acid on curing and those that do not. As might be anticipated the two part adhesive systems give a better cure in thick sections than do the single part types.
Phenolics
Phenolics were the first adhesives for metals and have a long history of successful use for joining metal to metal and metal to wood. They require heat and pressure for the curing process.
Polyimides
Polyimide adhesives are based on synthetic organic chains. They are available as liquids or films, but are expensive and difficult to handle. Polyimides are superior to most other adhesive types with regard to long term strength retention at elevated temperatures.
The following adhesives undergo a physical change and are less effective at forming the adhesive bond.
Hot Melts
Hot melts are based on modern thermoplastics and are used for fast assembly of structures designed to be only lightly loaded.
Plastisols
Plastisols are modified PVC dispersions that require heat to harden. The resultant joints are often resilient and tough.
Rubber Adhesives: Rubber adhesives are based on solutions or latexes and solidify through the loss of the medium. They are not suitable for sustained loadings.
Polyvinyl Acetate (PVA’s)
Vinyl acetate is the principal constituent of the PVA emulsion adhesive. They are suited to the bonding of porous materials, such as paper or wood, and to general packaging work.
Pressure-Sensitive Adhesives
Pressure sensitive adhesives are suited for use as tapes and labels and although they do not solidify they are often able to withstand adverse environments. This type of adhesive is not suitable for sustained loadings.