纯镍渗硼硅处理工艺及组织性能研究

Microstructure and Properties of Borosiliconized Pure Nickel

摘要:

采用粒状渗剂分别在渗硼硅温度为850、900、950 ℃，保温时间为2、8 h的工艺参数下对纯镍表面进行固体渗硼硅处理。用光学显微镜（OM）对渗层横断面进行了显微组织观察，用显微硬度计测试渗层的硬度分布，用M200型磨损试验机研究未渗硼硅和渗硼硅纯镍的耐磨性，采用循环氧化试验研究未渗硼硅和渗硼硅纯镍的抗高温氧化性。结果表明，纯镍渗硼硅后，渗层为硅化物层和硼化物层，且硅化物和硼化物的显微硬度都大于基体硬度，渗层厚度随着渗硼硅时间和温度的增加而增加，其范围约为36~237 mm，用X射线衍射仪（XRD）分析出渗层为硼化物层（Ni2B）和硅化物层（Ni3Si、Ni5Si2和Ni2Si）。磨损试验结果表明渗硼硅后试样的耐磨性得到提高。抗高温氧化试验结果显示未渗硼硅纯镍试样抗高温氧化性优于渗硼硅后纯镍试样

Abstract:

Borosiliconizing of 99.9% pure nickel was performed by a powder-pack method using borosiliconizing powders at 850, 900 and 950 °C for 2 and 8 h. The coated samples were characterized by Optical Microscope (OM), X-ray diffraction (XRD) and hardness tests. The oxidation behavior of unborosiliconized and borosiliconized pure nickel was studied with the kinetics curves of cyclic oxidation. The results show that boride (Ni2B) and silicide phases (Ni3Si, Ni5Si2 and Ni2Si) are formed on the surface of borosiliconized pure nickel, which are confirmed by X-ray diffraction analysis. Depending on boronizing time and temperature, the thickness of coating layer ranges from 36 to 237 mm. The hardness of the coating layer is much higher than that of pure nickel. Dry-sliding wear tests show that the wear resistance of borosiliconized pure nickel is greater than that of pure nickel. However, the oxidation test at 950 °C indicates that unborosiliconized sample possesses higher oxidation resistance than the borosiliconized sample.