An Introduction to Refractory Materials

1. An Introduction to Refractory Materials Whatare refractories?

2. What are refractories? • Refractories are heat-resistant materials that constitute the linings for high-temperature furnaces and reactors and other processing units. • They are made of natural and synthetic materials, usually nonmetallic, or combinations of compounds and minerals such as bauxite, chromite, dolomite, and others. • In general, refractories are used to build structures subjected to high temperatures, ranging from the simple to sophisticated, for example, fireplace brick linings to reentry heat shields for the space shuttle.

3. When and how were refractories developed? • The use of refractories began in the early 1950s, beginning with the linings formulated for the oxygen furnace. • An oxygen furnace is how a majority of steel is produced, at least about 60% in 2000. • Early materials, which consisted of pitch-bonded dolomite, were not heat-resistant enough to last very long before a furnace needed relining. • The issue of heat resistance was partially resolved by combining magnesium oxide with pitch-bonded dolomite. Refractories continued to develop and become better by our increase of knowledge of materials which could withstand temperatures of over 1000 degrees Celsius. This includes, of course, the development of synthetic materials • The discovery by Sidney Gilchrist Thomas and his cousin Percy Gilchrist in 1878 that phosphorus could be removed from steel melted in a dolomite-lined convertor was an important development. • -Thomas was actually a magistrate’s clerk in London, wanted to be a doctor, but happened to take a couple classes in chemistry and metallurgy. It took 3 tries over a one year period for the two to report success to the Iron and Steel Institute. • In 1931 it was discovered that the tensile strength of mixtures of magnesite and chrome ore was higher than that of either material alone, which led to the first chrome-magnesite bricks. OXYGEN FURNACE BLAST FURNACE

4. When and How were refractories developed? • Finally, not the least important development in refractories was the introduction of carbon clocks to replace fireclay refractories in the hearths of blast furnaces. • Initially the success of carbon blast furnaces led people to believe it would be the only way of making iron and steel in the future, however, it would soon be learned that there was not enough oxygen in these chambers to allow for such. Thus, oxygen furnaces remain the leader in making metals.

5. Who should care and why. • You should care because without refractory materials you wouldn’t have: • LIGHT! (Tungsten is a refractory metal used in most incandescent lighting) • HEAT! (Yes, the furnace and fireplace) • PIZZA! (most pizza ovens integrate refractory brick or material into their ovens)

6. Sources • Ceramic materials: science and engineering  By C. Barry Carter, M. Grant Norton • http://books.google.com/books?id=aE_VQ8I24OoC&pg=PA25&lpg=PA25&dq=history+of+refractories&source=bl&ots=RDx13tbDTt&sig=QQfrTFzSZzowBF9foypBglCpK3s&hl=en&sa=X&ei=Mf0dT7qrDIaFtgfoztivCw&ved=0CFkQ6AEwBw#v=onepage&q=history%20of%20refractories&f=false • “Refractory” via Wikipedia • http://en.wikipedia.org/wiki/Refractory • “The History of Refractories” via eHow • http://www.ehow.com/facts_7311362_history-refractories.html • “Cool Stuff Being Made: Refractories” via Youtube • http://www.youtube.com/watch?v=iGMLLroGKaA • “About Refractories” via The Refractory Institute • http://www.refractoriesinstitute.org/aboutrefractories.htm