Center for Innovative Sintered Products

Fundamental and Applied R&D in Sintered Materials

History of Sintering

Humans have used the process of sintering for thousands of years. Some of the first sintered products were bricks heated in open-pit fires to add strength. Sintered ceramic structures can be found around the world — examples include porcelain, a glass-bonded ceramic formed by sintering; and gold-platinum jewelry sintered by the Incas. Sintered materials today include powder metallurgy, cermets, polymers, ceramics, and cemented carbides.

Sintering is associated with engineered materials that are net-shaped with large production quantities and low production costs. Much commercial activity relies on net shaping using high-value-material systems such as cemented carbides, where powder compaction and sintering are the only viable options. The commercial value of sintered engineering materials (cermets, ceramics, and metals) is estimated at nearly $23 billion for 2003 (approaching 3 percent of the U.S. materials processing market). The annual growth rate in the use of sintered components ranges from 10 to 40 percent, depending on the industry.

Powders provide a fluid-like medium that can be shaped at low pressures. They allow a metallurgist to combine different elements to make an alloy, which can have properties better than any of the elements individually. Sintering is a thermal process (heat) applied to those shaped powders to bond them into essentially solid components. After sintering, a material's mechanical and physical properties often exceed those available through alternative forming processes.

The modern era of sintering is traced to Coolidge, who used tungsten powder to develop a durable lamp filament. Subsequently, spark plugs, cemented carbides, porous bronze bearings, electrical insulators, and copper-graphite electrical contacts were developed in the 1930s. In the latter part of the twentieth century there was enormous growth in sintering practice, especially for the creation of technical ceramics. Today, sintered materials are widely applied in engineering, especially for high-temperature systems ranging from light bulbs to jet engines. Sintered materials are also used in a diverse range of components that touch most industrial and consumer product areas — computer heat sinks, medical surgical tools, dental orthodontic brackets, automotive connection rods, electrical contacts, hand tools, postage meters, oil-well drilling tools, eyeglasses, wristwatch cases, golf clubs, and lawnmower transmissions, to name a few.

Sintered Materials and Powder Metallurgy in Pennsylvania

Pennsylvania enjoys a dominant position in powder metallurgy and related sintered engineering materials, with estimates placing up to 40 percent of the world's commercial activities inside the state. Over 15,000 Pennsylvanians are employed in this industry. The state has some of the world's largest ferrous, superalloy, tool steel, copper-based, refractory, and cemented carbide manufacturing operations. This industry includes a few firms with annual international sales approaching $2 billion.

Additionally, related activities occur in plastic powders and ceramics. In Pennsylvania, plastic powders are a small business, but ceramic processing is a large and well-developed industry representing annual sales in the USA over $5 billion.

The CISP effort was initiated by a grant from the Commonwealth of Pennsylvania, Department of Community and Economic Development, Pennsylvania Technology Investment Authority.