固体渗铬层组织结构及性能稳定性研究  

Structure and Performance Stability of Chromized Coatings by Pack Cementation

作　　者：韦春贝 林松盛 代明江 石倩 苏一凡 唐鹏 Wei Chunbei;Lin Songsheng;Dai Mingjiang;Shi Qian;Su Yifan;Tang Peng(Guangdong Institute of New Materials,National Engineering Laboratory for Modem Materials Surface Engineering Technology,The Key Lab of Guangdong for Modem Surface Engineering Technology,Guangzhou 510651,China)

机构地区：[1]广东省新材料研究所现代材料表面工程技术国家工程实验室,广东省现代表面工程技术重点实验室,广东广州510651

出　　处：《稀有金属材料与工程》2021年第5期1706-1712,共7页Rare Metal Materials and Engineering

基　　金：广东特支计划(2019BT02C629);广东省科学院创新能力建设项目(2018GDASCX-0111);广东省重点领域研发计划(2020B010184001)。

摘　　要：采用固体粉末法在GCr15钢表面进行渗铬处理,研究了不同渗铬时间下渗层的结构和性能,并研究了自然时效对渗层结构、力学性能的影响。采用扫描电子显微镜及EDS能谱仪、X射线衍射仪研究了时效前后渗层组织结构的变化,采用显微硬度仪、纳米压痕仪、洛氏硬度计分析了时效前后渗层表面硬度、截面微区硬度、与基体的结合强度。结果表明:渗层主要由Cr_(2)N、(Cr,Fe)_(23)C_(6)和(Cr,Fe)7C3相组成,渗层外表面为不连续的氮化铬晶粒分布在疏松的碳化铬中,随着渗铬时间的增加,氮化铬晶粒长大;渗层下表面为碳化铬层,由外向内Cr逐渐减少,Fe逐渐增加,形成了梯度过渡层结构。渗层表面显微硬度(HV0.05)在14920~16980 MPa之间,经过1a自然时效后表面显微硬度稍有降低;截面纳米硬度表明,随着Cr含量逐渐减少,纳米硬度也相应下降。洛氏压痕结果表明,压痕周围存在放射性裂纹及不同程度的渗层剥落现象;经过1a自然时效后压痕周围只存在放射性裂纹,渗层与基体结合强度提高。Chromized coatings were fabricated on GCr15 steel using a conventional pack-cementation method.The effect of chromizing time,as well as natural ageing on the structure and performance was investigated.The phases and microstructure were characterized by scanning electron microscopy(SEM)with EDS and X-ray diffraction(XRD).The microhardness of the surface,the nanohardness of cross-section,the adhesion strength of the coatings were characterized by Vickers microhardness tester,nano-indenter and Rockwell-C tester.The results show that the chromized coatings are composed of Cr_(2)N,(Cr,Fe)_(23)C_(6)and(Cr,fe)7 C3.In the top surface,the discontinuous Cr_(2)N crystal grains distribute in the loose chromium carbides.The Cr_(2)N crystal grains grow larger as the chromizing time increasing.In the sublayer,the phase is composed of chromium carbides.The gradient structure is formed in the chromized coatings with Cr content decreasing from surface to substrate and the contrary trend for Fe content.The microhardness(HV0.05)of the surface is between14920-16980 MPa and it decreases slightly after 1 year natural aging.The nanohardness reduces with Cr content decreasing in cross-section of chromized coatings.The Rockwell-C test results show that there are some radial cracks and spalls around the indentation craters.However,only radial cracks are presented around the indentation craters after 1 a natural aging,indicating the improvement of adhesion strength of the coatings to substrate.

关 键 词：固体渗铬 自然时效 相结构 硬度 结合强度 

分 类 号：TG156.8[金属学及工艺—热处理] TG174.4[金属学及工艺—金属学]