摘要
加入稀土氧化物可改善喷焊层的组织结构,提高涂层硬度。采用等离子喷焊工艺在20钢表面制备不同添加量La2O3的镍包铝合金喷焊层。通过光学显微镜、SEM、能谱仪、X射线衍射仪、显微硬度、热震试验以及高温摩擦磨损试验,研究了La2O3对喷焊层组织结构与性能的影响。结果表明:镍包铝等离子喷焊层显微组织的主体形态为树枝晶,树枝晶内部为α-(Fe,Ni)板条马氏体群,晶间网状组织为γ-(Fe,Ni);这种组织结构使镍包铝等离子喷焊层在750℃仍保持较好的抗热震性;添加0.5%La2O3后镍包铝喷焊层硬度提高了19.4%,但对喷焊层抗热震性能无明显改善;镍包铝喷焊层在500℃时的高温摩擦磨损试验中表现出较好的摩擦稳定性和理想的高温耐磨性能,这是因为其组织结构中存在韧性较好的晶间γ-(Fe,Ni)组织,呈网状包裹着强硬度较高的α-(Fe,Ni)板条马氏体,因而不易在磨损时发生剥离现象。添加0.5%La2O3可使其高温耐磨性能达到最佳;当La2O3添加量达1.0%时,镍包铝等离子喷焊合金层的硬度、抗热震性能以及高温耐磨性能较0.5%添加量时有所下降。
Adding rare-earth oxides could improve the structure and hardness of sprayed welding coatings.The sprayed nickel-coated aluminum coatings with adding different La2O3 contents were prepared on the surface of 20 steel by plasma spray welding.The microstructure and performance of coatings were studied by optical microscopy,SEM,EDS,X-ray diffractometer,micro-hardness tester,thermal shock test and high-temperature wear test.Results showed that the microstructures of nickel-coated aluminum plasma sprayed layer were dendrites,and the dendrites were some lathα-(Fe,Ni)martensite groups with intergranular reticular phase ofγ-(Fe,Ni).These structures endowed the nickel-coated aluminum plasma sprayed coatings with good resistance of thermal shock at 750℃.The addition of 0.5%La2O3 improved the hardness of the nickel-coated aluminum plasma sprayed layer by 19.4%,but did not have obvious effect on the resistance of thermal shock.In addition,nickel-coated aluminum spray welding coating showed a good friction stability and ideal-high temperature wear resistance in high-temperature friction and wear tests at 500℃,which resulted from that the tissue structure possessed theγ-(Fe,Ni)intercrystalline tissues with good toughness and high-strength latitudinarianα-(Fe,Ni)slabs.When 0.5%La2O3 was added,the high-temperature wear-resistant performance of obtained coating reached optimal.However,when the addition of La2O3 was 1.0%,the hardness,resistance of thermal shock and resistance of high-temperature wear of the nickel-coated aluminum coating decreased,compared with the coating prepared with the La2O3 addition of 0.5%.
作者
王怀伟
王艳阳
WANG Huai-wei;WANG Yan-yang(Testing Center of Ma’anshan Iron and Steel Co.,Ltd.,Ma’anshan 243000,China)
出处
《材料保护》
CAS
CSCD
北大核心
2019年第6期52-57,共6页
Materials Protection
关键词
等离子喷焊
镍包铝合金层
LA2O3
高温耐磨性能
组织结构
plasma spray welding
nickel-coated aluminum coating
La2O3
high-temperature wear resistance
microstructure
作者简介
通信作者:王怀伟(1993-),硕士研究生,助理工程师,主要研究方向为材料表面处理、金属材料物理性能检验,电话:18355517951,E-mail:1401123291@qq.com
