钎焊气氛对金刚石磨粒与钎料界面微观结构的影响

在真空和Ar气两种不同的氛围中，采用NiCr合金钎料，进行了炉中钎焊金刚石磨粒的试验研究。运用扫描电镜（SEM）、X-射线能谱仪（EDS）和X-射线衍射结构研究了不同钎焊气氛对NiCr合金钎料成分和金刚石磨粒与钎料界面微观结构的影响。结果表明：（1）在不同的钎焊气氛下，由于氧分压的不同导致了NiCr合金钎料的成分也不相同。在Ar气保护气氛下的炉中钎焊金刚石试样表面有B2O3生成。（2）在不同钎焊气氛中，在金刚石磨粒与合金钎料界面生成物都主要为铬的碳化物。但生成物表面形貌不同，在真空炉中焊后的金刚石磨粒表面生成物成放射状生长，而在Ar气保护炉中钎焊后的金刚石磨粒表面生成物如杂草一样生长且生成物组织较真空炉中细小。

EFFECTS OF BRAZING ATMOSPHERES ON INTERFACIAL MICROSTRUCTURE BETWEEN DIAMOND GRITS AND BRAZING ALLOY

The samples of brazed diamond grits with NiCr brazing alloy are prepared in vacuum and argon gas. The microstructures are analyzed with scanning electron microscope(SEM), energy dispersive X-ray spectroscopy(EDS) and X-ray diffraction(XRD). The effects of brazing atmospheres on the as-brazed NiCr brazing alloy composite structures and interfacial microstructure are studied between diamond grits and brazing alloy. Results show that: (1) There are different composite structures of as-brazed NiCr brazing alloy under different oxygen partial pressures in vacuum and argon gas. B2O3exists on the surface of the brazed samples under argon gas furnace brazing. It indicates that oxygen plays an important role in the resultants of as-brazed NiCr brazing alloy during the brazing process. (2) There are different interfacial microstructures in different brazing atmospheres, but the main reaction product is chromium carbides. The chromium carbides in argon gas furnace brazing grow in a disordered form, but those in vacuum furnace brazing grow radiated. And the scale of grains in argon gas is smaller than those in vacuum.