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In several plants,a few NH4C1 are added to Al2O3 (as a packing material) during the activated sintering process of sintered carbides in order to lower the sintering temperature from 1450℃ to about 1250℃, whereas corundum tubes of sintering furnace deteriorate abnormally, A thermodynamical analysis has been given in this paper to exlpain the deterioration mechanism. It is shown that the cause of the abnormal deterioration of corudum tubes is that the CaO impurity, as a constituent included in... In several plants,a few NH4C1 are added to Al2O3 (as a packing material) during the activated sintering process of sintered carbides in order to lower the sintering temperature from 1450℃ to about 1250℃, whereas corundum tubes of sintering furnace deteriorate abnormally, A thermodynamical analysis has been given in this paper to exlpain the deterioration mechanism. It is shown that the cause of the abnormal deterioration of corudum tubes is that the CaO impurity, as a constituent included in tube material, reacts chemically with HCl gas decomposed from NH4Cl at high temperature. The conclusion has been verified by experiments and it will not be affected by the existent forms of different impurities. 本文从热力学计算及实验结果,探讨了活化烧结硬质合金时烧结炉刚玉炉管非正常损坏的机理。对制订特殊烧结工艺,有一定参考价值。 Among the corrosion resistant hard metals an investigation for the corrosion resistance of the WC base metal is of particular importance, since this metal is more universal in use. In this article, the corrosion resistance of the WC base hard metal to acid and alkali and its relations to the contents and compositions of the bonding phase, as well to as the graphite and η_1 phase in the metal are discribed and on this basis the activated sintering of the hard metals of low bonding phase contents is discussed.... Among the corrosion resistant hard metals an investigation for the corrosion resistance of the WC base metal is of particular importance, since this metal is more universal in use. In this article, the corrosion resistance of the WC base hard metal to acid and alkali and its relations to the contents and compositions of the bonding phase, as well to as the graphite and η_1 phase in the metal are discribed and on this basis the activated sintering of the hard metals of low bonding phase contents is discussed. 在耐蚀硬质合金中,WC基硬质合金占有很大比重,因此研究该类合全的耐蚀性是很有必要的。本文就WC基硬质合金在酸、碱中的抗蚀性及其与粘结相含量、成分以及合金中的石墨、η_1相等的关系进行了研究。并在此基础上,对低粘结剂含量的硬质合金的活化烧结进行了探讨。WC基硬质合金的耐蚀性,主要由粘结剂的抗蚀性所决定,并与其含量相关。以Ni、Mo、Co、Cr为粘结剂的合金的抗蚀性远远优于WCCo类合金。WC基硬质合金的抗蚀性与WC相晶粒尺寸及少量异种碳化物(Cr_3C_2、Mo_2C)、合金中的石墨和η_1相的存在有关。具有较好耐蚀性的低粘结剂硬质合金,可以采用化学混合制取复合粉末、强化球磨、活化烧结的工艺制备。WC—Ni·Mo·Co·Cr系硬质业合金是制作圆珠笔球的理想材料。 The present paper studies the influence of quantity of palladium added in molybdenum, sintering temperature and sintering time on densities of molybdenum The experiments show that optimum quantity of palladium is around 0.5wt.%.The optimum sintering temperature of molybdenum with about 0.5wt.% pd is at 1150℃.The characteristic exponent(n) for indicating dominant densifieation mechanism and apperent activation energy(Q) were calculated by using experimenltal data.The n and Q obtained is 3.1-3.4 and 61-62.5 kcal... The present paper studies the influence of quantity of palladium added in molybdenum, sintering temperature and sintering time on densities of molybdenum The experiments show that optimum quantity of palladium is around 0.5wt.%.The optimum sintering temperature of molybdenum with about 0.5wt.% pd is at 1150℃.The characteristic exponent(n) for indicating dominant densifieation mechanism and apperent activation energy(Q) were calculated by using experimenltal data.The n and Q obtained is 3.1-3.4 and 61-62.5 kcal mol~(-1) respectively. It is concluded that the activated sintering mechanism of molybdenum by palladium is mainly derived from boundary diffusion. Some cosiderations of the distribution state of palladium on the surface of molybdenum particles are also given in this paper 本文研究了钯的加入量、烧结温度和烧结时间对钼的密度的影响。实验结果表明,钯的最适宜的加入量为0.5wt%左右。在这个最佳量下钼的最适宜的烧结温度为1150℃。利用实验数据计算了钯活化钼烧结的控制收缩机理的特性指数n和表观活化能Q。得习n为3.1—3.4和Q为61—62.5kcal/mol。从而得出钯活化钼的烧结机理以晶界扩散为主。本文对钯在钼粉粒子表面上的分布状态,提出了看法。
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