硬质合金模压成型收缩系数对压制性能与物理性能的影响

Effect of Shrinkage Coefficient on Compaction and Physical Property of Cemented Carbide Die Forming

选用5μm、3μm和0.8μm晶粒度的WC混合料为原料,研究不同模压收缩系数条件下、硬质合金产品的压制性能与物理性能。利用试验结果建立了收缩系数与压制压力之间的指数方程关系式。指数方程表明:随着收缩系数增大,压制压力呈指数曲线降低,压制弹性后效也随之减小;随着混合料WC晶粒度减小,压制压力与弹性后效随之增大。压制5μm、3μm和0.8μmWC晶粒度的混合料时,以压坯不出现裂纹为标准,确定最小收缩系数应分别不小于16.5%、16.5%以及17%。当收缩系数从16%增大到20%,硬质合金产品的孔隙度与抗弯强度在某一收缩系数点处出现明显的物理性能变差趋势,因此,5μm、3μm和0.8μmWC晶粒度的模具收缩系数应分别≤17.5%、18.5%及19%。

By Using WC mixture with grain size of 5μm,3μm and 0.8μm as raw material,the compaction and physical properties of cemented carbide products under different molding pressure shrinkage coefficient are studied.Based on the experimental results,the exponential equation between the contraction system and the pressing pressure is established.The exponential equation shows that the compression pressure decreases with the increase of the shrinkage coefficient.At the same time,the elastic aftereffect is reduced.As the grain size of WC mixture decreases,the pressing pressure and elastic aftereffect increase accordingly.For the mixture with grain size of 5μm,3μm and 0.8μm,the minimum shrinkage coefficient should be determined at the time of crushing and crack,which should be no less than 16.5%,16.5% and 17% respectively.When the contraction coefficient increases from 16% to 20%,the porosity and bending strength of cemented carbide products are at a particular point appear obvious shrinkage coefficient physical property variation trend,so 5μm,3μm and 0.8μm WC grain size mold shrinkage coefficient should be no greater than 17.5%,18.5% and 19% respectively.