Additives liquid-phase sintering

Fig. 19.5. Liquid phase sintering a small amount of additive forms a liquid which accelerates sintering and gives fully dense products but with some loss of high-temperature strength.

A new type of liquid-phase sintered SiC using yttria [1314-36-9J, Y20, as the oxide additive and submicrometer SiC powder for enhanced densification, produces a material which can be densified without the application of pressure (13). This material, sintered from cold isostatically pressed billets, appears to be comparable to silicon nitride in strength and fracture toughness. 

As an other possibility we find out that the liquid phase sintering of a W-Cu gradient with 0-20 vol.-% copper and 0,25% Co as additive results in an porosity gradient from 30% to 75%. After infiltration it leaves to a W-Cu gradient with 30-80 vol.-% copper and a nearly linear gradient function over the whole dimension (3 mm) of the sample. 

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