Production of carbon fiber-tantalum carbide composites

摘要

Carbon fiber reinforced tantalum carbide composites are produced by vacuum infiltration of omni-weave carbon, e.g. three dimensional graphite, yarn preforms with an aqueous saturated solution containing tantalum fluoride and sucrose. Anhydrous ammonia is added under pressure, forming ammonium fluoride, which is removed by vacuum sublimation by application of heat. The resulting preform containing tantalum pentoxide and partially pyrolyzed sucrose is heated at high temperature and reduced pressure to decompose the sucrose to yield active carbon which reacts with the tantalum pentoxide to yield tantalum carbide and carbon monoxide. After repeated multiple infiltrations and processing, a composite is produced having a matrix of tantalum carbide or tantalum carbide and carbon, which is reinforced in three or more directions with high strength-high modulus carbon or graphite yarn, the amount of carbon in the matrix phase being a function of the amount of sucrose present in the aqueous solution of tantalum fluoride.