研究了用化学镀ＮｉＰ合金的方法预先将Ｓｉ３Ｎ４表面金属化，再用普通２９７＃ＰｂＳｎＺｎＳｂ焊料对Ｓｉ３Ｎ４与４５＃钢进行低温钎焊。结果表明，用上述工艺方法可以实现Ｓｉ３Ｎ４与４５＃钢的连接。当工艺条件合适时，接头断裂发生在Ｓｉ３Ｎ４与ＮｉＰ合金镀层之间的结合面上，最大抗剪切断裂强度约为８０ＭＰａ。Ｘ射线衍射应力分析结果表明，Ｓｉ３Ｎ４表面ＮｉＰ合金镀层的内应力对低温钎焊接头的抗剪切断裂强度有直接影响。在Ｓｉ３Ｎ４表面化学镀ＮｉＰ合金后，采用４００℃下保温尽可能长时间的热处理工艺，可最大限度地降低镀层中的内应力，使钎焊接头的强度提高。 The method of electroless Ni-P alloy plating was used to metallize the surface of Si3N4 in advance, and then the Si3N4 and 45 # steels were brazed at low temperature by ordinary 297 # Pb-Sn-Zn-Sb solder. The results show that, with the above process can be achieved Si3N4 and 45 # steel connection. When the process conditions are suitable, the joint fracture occurred in the interface between Si3N4 and Ni  P alloy coating, the maximum shear strength of about 80MPa. X-ray diffraction stress analysis results show that the internal stress of Ni  P alloy coating on Si3N4 surface has a direct impact on the shear strength at low temperature brazed joints. Si3N4 surface chemical plating Ni  P alloy, the use of 400 ℃ as long as possible heat insulation process, can minimize the internal stress in the coating, so that the strength of the brazed joints.