离子后氧化对渗氮层结构与性能的调控  

Regulation of Structure and Properties of Nitriding Layer by Post Plasma Oxidation

作　　者：倪嘉 麻恒 于民华 胡静[1,2,4] 安旭龙 魏坤霞 NI Jia;MA Heng;YU Minhua;HU Jing;AN Xulong;WEI Kunxia(Jiangsu Key Laboratory of Materials Surface Science and Technology,Changzhou University,Jiangsu Changzhou 213164,China;National Experimental Demonstration Center for Materials Science and Engineering,Changzhou University,Jiangsu Changzhou 213164,China;Jiangsu Shuangliang Boiler Co.,Ltd.,Jiangsu Jiangyin 214444,China;Huaide College,Changzhou University,Jiangsu Jingjiang 214500,China)

机构地区：[1]常州大学江苏省材料表面科学与技术重点实验室,江苏常州213164 [2]常州大学材料科学与工程国家级实验教学示范中心,江苏常州213164 [3]江苏双良锅炉有限公司,江苏江阴214444 [4]常州大学怀德学院,江苏靖江214500

出　　处：《表面技术》2024年第17期170-175,共6页Surface Technology

基　　金：国家自然科学基金(21978025,51774052);江苏省第三期优势学科建设项目(PAPD-3);江苏高校品牌专业建设工程资助项目(TAPP)。

摘　　要：目的调控离子渗氮层的结构和性能,获得少无化合物层且满足需求厚度的有效硬化层,同时具有良好的韧性和耐蚀性的离子渗层。方法将42CrMo4钢在温度500℃下离子渗氮5 h后,再进行不同工艺条件下的后氧化处理。通过调整后氧化的实验参数,探索它们对渗氮层结构和性能的影响规律。使用金相显微镜、XRD衍射仪、维氏显微硬度计及电化学工作站分析截面渗层结构、物相、硬度、韧性和耐蚀性。结果在相同的离子渗氮条件(500℃,5 h)下,随着后氧化的温度和时间的改变,离子渗氮形成的化合物层逐渐分解,化合层的厚度逐渐减小,可由9.41μm减薄至3.62μm;经离子渗氮+后氧化处理后,形成的有效硬化层的厚度和表面硬度相较于常规离子渗氮有所提高,其中有效硬化层的厚度由300μm增至378μm,截面最高硬度由765HV0.05增至825HV0.05;渗层表面形成由Fe_(3)O_(4)、Fe_(2)O_(3)组成的氧化膜,提高了其耐蚀性,自腐蚀电位由-658.72 mV提升至-429.23 mV。结论42CrMo4钢经过离子渗氮及后氧化处理后,化合物层显著减薄,有效硬化层显著增厚,且截面硬度、韧性和耐蚀性等指标均得到改善,在后氧化工艺参数为400℃、2 h时获得了最优的综合性能,包括硬度、韧性、耐蚀性。Plasma nitriding is an environment-friendly and efficient surface modification technology.A nitrided layer composed of a compound layer on the top surface and a diffusion layer beneath can be formed on the surface of the sample treated by plasma nitriding,thus improving the performance of the sample.However,since the compound layer is hard and brittle,it has a strong tendency to crack while being subject to severe and heavy load,such as heavy load gears and impact molds.Therefore,it is necessary to avoid thicker compound layers for components that suffer severe impact and heavy load wear in order to prevent premature failure.At present,most factories use grinding to reduce the thickness of the compound layer,but this method has obvious disadvantage because it is difficult to control the grinding amount.Therefore,in order to obtain the required thickness of the effective hardened layer with fewer compound layers,it is crucial to find a technique to regulate the structure of the plasma nitriding layer,which has significant scientific research and application value.The work aims to explore and develop a novel method to regulate the structure of the plasma nitriding layer.The method was used to conduct post oxidation after plasma nitriding.The whole process was consisted of the following two steps:firstly,42CrMo4 steel was subject to plasma nitriding at 500℃for 5 hours and secondly,post oxidation was carried out at different temperatures for different time.The effect of the post oxidation temperature and time on the structure of the plasma nitriding layer was systematically investigated and the related mechanism was analyzed.The optical microscope,X-ray diffractometer,Vickers microhardness tester,and electrochemical workstation were used to examine and assess the microstructures,phase composition,hardness,toughness,and corrosion resistance of the nitriding layer.After the same plasma nitriding conditions of 500℃for 5 hours,it was found that with the change of the post oxidation temperature and time,the compound l

关 键 词：42CrMo4钢 离子渗氮 离子后氧化 硬度 韧性 耐蚀性 

分 类 号：TG156.8[金属学及工艺—热处理]