Effect of microstructure on properties of NiCrBSi alloys applied by flame-powder deposition

This article deals with studying the relationships among the chemical composition, microstructure and properties (hardness, micro-hardness, wear resistance) of powder additives based on NiCrBSi after their deposition. Tested materials reached a relatively wide range of hardness after deposition, which corresponds to their chemical composition and microstructure. The abrasive wear resistance of materials was tested on an emery cloth. The results indicate that both the hardness and abrasive wear resistance of tested materials depend especially on the content of carbon and chromium. Microstructural analysis indicates that the structure of tested materials is formed by the γ-Ni solid solution and intermediate phases based on boron, silicon and carbon. Those mostly form eutectics (three types), or are excluded by precipitation. There was also found a significant effect of chromium, but especially carbon content on the ratio between the solid solution and eutectics in the microstructure of tested materials. These different ratios of solid solution and eutectics were markedly reflected in micro-hardness behaviours in deposited layers. Micro-hardness values confirmed also the presence of carbidic particles in the layers with carbon content higher than 0.7 wt%. © (2014) Trans Tech Publications, Switzerland.