Six firms produced silicon carbide in 1971 in the United States and Canada. The Carborundum Co. operated plants in both countries and Electro-Refractories & Abrasives, Ltd., The Exolon Co., General Abrasive Co., Division of U.S. Industries, and Norton Co. operated in Canada, all of which produced crude for abrasive, refractory, and miscellaneous uses. Satellite Alloy Corp., which has facilities only in the United States, produced silicon carbide for refractories and other nonabrasive applications. Production was estimated at 66 percent of capacity and consumption was estimated at about 52 percent for abrasive use and 48 percent for nonabrasive purposes. As of December 31, 1971, GSA reported 427,725 short tons of fused, crude aluminum oxide in inventory, of which 127,725 tons was in excess of the objective of 300,000 tons; 50,905 tons of fused aluminum oxide abrasive grain at objective; and 196,453 tons of silicon carbide crude, of which 166,453 tons were in excess of the objective of 30,000 tons. Manufacture of metallic abrasives in 1971 decreased 7 percent each in quantity and value compared with 1970, and the quantity manufactured was only slightly greater than the quantity sold or used. Steel shot and grit was 76 percent of the total sold or used, followed by chilled iron shot and grit at 13 percent, annealed iron shot and grit at 10 percent, and other metallic oxides and carbides at 1 percent. Ohio was the leading producing state with 28 percent of the total quantity. Michigan, Pennsylvania, and Indiana followed in order of quantity, and their combined total was 63 percent. Alabama, New York, and Connecticut accounted for the remaining 9 percent of quantity. Producers of metallic abrasives were as follows: Table 12.-Crude artificial abrasives produced in the United States and Canada (Thousand short tons and thousand dollars) 1 Figures include material used for refractories and other nonabrasive purposes. 2 Shipments for U.S. plants only. Data may not add to total shown because of independent rounding. Table 13.-Production, shipments, and stocks of metallic abrasives in the United States, 1 The total quantity of the various types of metallic abrasives that a plant could have produced during the year, working three 8-hour shifts per day, 7 days per week, allowing for usual interruptions, and assuming adequate fuel, labor, and transportation. 2 Included in capacity of chilled iron shot and grit. Includes cut wire shot. Data may not add to total shown because of independent rounding. Table 14.-Stocks of crude artificial abrasives and capacity of manufacturing plants, as reported by producers in the United States and Canada TECHNOLOGY In the design of new abrasives, the important abrasive grain properties of hardness and toughness must be related. Structural and chemical factors affect grinding that must be related to the properties.25 An overview of the abrasive industry, worldwide, was presented in three magazine articles.26 A book was published on "Abrasive Materials Sciences."27 Transmission electron microscopy provided direct evidence that plastic deformation occurs during the room-temperature indentation and abrasion of single-crystal and polycrystalline aluminum oxide.28 The addition of a small percentage of vanadium to molten aluminum oxide resulted in a green-colored alloyed abrasive which has superior properties, according to the claims of its producers.29 The total number of patents on the ma terials used in abrasives and refractories was large, although most were aimed at improvements of existing materials and the machines that use abrasives and refractories. Numerous magazines and journals described new products, patents, and processes, of which the preceding excerpts are a sampling. 25 Ueltz, Herbert F. G. New Developments in Abrasive Grain. Technical Paper MR 71-109, pres. at the meeting of the Society of Manufacturing Engineers, Philadelphia, Pa., April 1971. 26 Industrial Minerals. An Introduction to Abrasives: Natural Gives Way to Synthetic. No. 45, June 1971, pp. 9-11. Diamond: pp. 13-28. Industrial Minerals. Abrasives: Uses Widening but Improved Quality Moderating Demand. No. 46, July 1971, pp. 9-28. 27 Coes, L., Jr. Abrasives. Applied Mineralogy. V. 1. Springer-Verlag, New York, 1971. 28 Hockey, Bernard J. Plastic Deformation of Aluminum Oxide by Indentation and Abrasion. J. of the Am. Ceramic Sec., v. 54, No. 5, May 1971, pp. 223-232. 29 McKee, Richard L. Aluminum Oxide Alloy Improves Hard-Steel Grinding. Abrasive Eng., v. 17, No. 8 November/December 1971, pp. 26-27. Staff. Grinding Industry Turns to Alloyed Abrasive. Iron Age, v. 28, No. 18, Oct. 28, 1971, pp. 48-49. By John W. Stamper 1 Total world aluminum production capacity in 1971 was 13,686,000 short tons, an increase of 14 percent over world capacity in 1970 resulting from expansions at existing plants and to installation of new plants. The increases built into existing, privately owned plants throughout the world amounted to 620,000 tons in 1971 compared with 42,000 tons for plants that were partly or fully government-owned. The increase in world capacity due to new, privately owned plants was 919,000 tons compared with 68,000 tons for new plants which were partly or fully owned by government. 1 Physical scientist, Division of Nonferrous Metals. |