等离子渗氮、离子镀TiN复合处理对纯钛铸件硬度及耐磨性的影响

纯钛铸件进行等离子渗氮、脉冲真空电弧离子镀TiN薄膜复合处理后,扫描电镜观察表面形貌,显微硬度仪测量硬度,球盘磨擦实验评估耐磨性。结果显示钛铸件渗氮、TiN镀膜复合处理后,表面呈现均匀明亮的金黄色,显微硬度和耐磨性均显著提高,且优于单纯镀TiN膜的钛铸件。此方法应用于口腔医学领域,对义齿钛支架进行表面改性处理,可提高其磨擦学性能,改善颜色。     

纯钛材离子渗氮后在Hank’s人工模拟体液中的电化学性能

为了提高纯钛材的表面硬度及耐蚀性,使之更适应人体环境,对铸态纯钛材表面进行离子渗氮。利用能谱仪、X射线衍射仪、扫描电镜及显微硬度计研究了渗氮钛材的成分、相结构、形貌及硬度,利用动电位极化曲线及交流阻抗谱对比研究了纯钛材及离子渗氮钛材在37℃的Hank’s人工模拟体液中的电化学行为。结果表明:经过650℃渗氮处理后,铸态纯钛材表面形成了17μm的梯度渗氮层,其相组成为α-Ti(N),Ti2N,TiN;表面显微硬度约为(650±20)HV,为铸态纯钛材的2.3倍;离子渗氮钛材的耐蚀性明显提高。     

G105石油钻杆表面等离子渗氮组织和耐磨耐蚀性能分析

为了提高G105石油钻杆表面的耐磨耐蚀性能,通过在钻杆内部插入辅助阳极的等离子渗氮工艺对其表面进行处理,研究了不同测点深度对渗氮层组织和耐磨耐蚀性能的影响。研究结果表明:随着测点深度的增加,钻杆表面的温度表现出先增加后降低的变化规律,最大值发生在测点2。测点1～3部位形成了部分白亮层与扩散层,在白亮层中与试样表面平行的区域产生了黑色富氮层。按照从外往里的方向,渗层内的氮含量不断减小,在扩散阶段氮原子和铁原子发生结合并生成金属间化合物。通过离子渗氮处理后,试样腐蚀速率降低,渗层可以发挥良好的抗腐蚀性能,有效增强基体的耐蚀性。渗氮层摩擦系数减小至接近0.500的状态,随位置深度增加磨损率逐渐增大。在测点1～3部位磨痕表面较光滑平整,没有出现明显的犁沟、划痕等现象。     

表面纳米化与离子渗氮对304不锈钢的影响

为解决304不锈钢硬度低、耐磨性差的问题,本文采用预先表面纳米化,温度400、450℃,保温时间4、6 h,氮氢比1∶3的离子渗氮工艺对试样进行处理,研究纳米化以及渗氮工艺对304不锈钢渗氮层形貌和深度、硬度以及摩擦磨损性能的影响.利用金相显微镜、电子探针显微分析仪(EPMA)、能谱仪(EDS)、显微硬度计和磨损试验机对样品的显微组织、微观形貌、硬度及耐磨性进行了表征.结果表明:304不锈钢经表面纳米化与离子渗氮工艺处理后,渗氮层为0.1～0.2 mm,表面硬度约为1 200 HV0.1,比基体硬度提高了6～7倍,耐磨性也大大增强;但渗氮温度越高,保温时间越长,材料表面耐磨性越差.综合各种影响因素得出在本实验条件下最佳处理工艺为:预先表面纳米化,渗氮温度400℃、保温时间6 h.     

离子渗氮对耐磨性的影响

对四种离子渗氮工艺条件下的３８ＣｒＭｏＡｌ新渗氮钢进行了磨损试验研究。通过Ｘ射线衍射表面相结构分析以及测量表明硬度，截面硬度梯度，化合物层厚度和渗氮层深度等试验结果表明，离子渗氮前的原始组织对３０Ｃｒ２ＭｏＶ钢耐磨性影响较小，而对３８ＣｒＭｏＡｌ钢的耐磨性影响较大。离子渗氮工艺条件对这两种钢耐磨性具有一最佳值。     

初始状态对形变及热处理后工业纯钛组织和力学性能的影响

利用Gleeble 3800热模拟试验机对退火态和淬火态的工业纯钛进行多道次平面应变压缩,研究不同初始状态经过压缩变形和热处理后的组织和性能的演变规律。通过流变曲线、组织观察和显微硬度分析表明:退火态相对于淬火态变形组织较为均匀且变形抗力低10~25MPa,显微硬度也较低。经过不同工艺热处理后,工业纯钛淬火态的组织不均匀性未得到消除且出现混晶现象,淬火态与退火态的显微硬度趋于一致。     

功率对纯钛薄片激光封孔成形及接头性能的影响

为实现直径为0.1 mm微孔的良好封接,采用低功率脉冲激光对0.40 mm厚的工业纯钛(CP-Ti Grade 1)进行了封焊,采用扫描电镜、显微硬度计及光学显微镜,研究了激光功率对焊缝表面成形、焊接接头横截面形貌和显微硬度的影响规律,分析了接头的微观组织结构.结果表明:当激光功率不低于19.2 W时,微孔可以实现完全封接,且熔核直径随着激光功率的增大而增大,但随着激光功率增大,焊缝凹陷和烧蚀现象越加严重;当激光功率增大时,焊缝表面显微硬度呈上升趋势,激光功率为19.2 W时,焊缝成形良好,且最大显微硬度值可以达到290 HV;焊缝中心微观组织为针状α、锯齿状α以及板条状α晶,焊缝上边缘为锯齿状α晶,而焊缝下边缘为细小的锯齿状α和针状α晶.     

热处理对高耐磨性NiTi基合金材料性能的影响

通过光学金相和显微硬度实验的分析方法,研究了热处理制度对高耐磨性NiTi合金材料性能的影响.实验表明,NiTi耐磨材料经过不同的热处理工艺后,材料的硬度变化明显,在800℃×30min/WQ+300℃×240min/FC热处理工艺制度下其硬度值最高;800℃固溶处理后,随着300℃时效时间的延长,材料显微组织鱼骨状晶逐渐增加,线状晶逐渐减少;黑色颗粒状质点逐渐增加,基体得到强化,材料显微硬度逐渐升高.随着冷却速度的增加,材料的晶粒得到细化.     

等离子钛表面冶金技术

采用双层辉光放电产生的低温等离子体在纯钛表面制备了表面合金,开发出了在钛表面制备Ti-C合金和Ti-Zr合金等的工艺方法.     

纯钛表面仿生矿化性能优化的研究

采用不同的碱液处理浓度和处理时间在80℃下处理纯钛的表面并在模拟体液(SBF)中进行仿生矿化.结果表明随着碱液处理浓度和处理时间的增加,纯钛表面在模拟体液中仿生矿化的能力增强.碱液处理的浓度是影响纯钛表面仿生矿化能力的主要因素.经10M/L的碱液处理48h后,纯钛表面生成的是具有(002)和(004)晶体取向的类骨磷灰石(HCA),HCA晶粒生长较大,相互连接形成空间紧凑的结构.     

等离子体浸没离子注入和沉积技术制备TiN薄膜研究

利用多功能等离子体浸没离子注入设备 ,采用等离子体浸没离子注入和沉积技术在Ti合金表面制备具有优异力学性能的TiN薄膜。研究了真空室中氮气存在状态及氮气压力对薄膜性能的影响 :当氮以中性气体存在于真空室中 ,薄膜的生长主要受热力学因素控制 ,沿着低自由能的密排面 (低指数面 )TiN(1 1 1 )择优生长 ;当氮以等离子体状态存在于真空室中 ,薄膜沿着高指数面TiN(2 2 0 )择优生长 ,具有高硬度、耐磨性好的优点 ,并且随着N分压的提高 ,薄膜耐磨性提高     

二次调质离子渗氮工艺参数对35CrMo耐磨性的影响

文中通过对35CrMo进行热处理,采用一次调质＋亚温淬火＋回火＋离子渗氮的方法提高材料的耐磨性。采用不同的回火温度、渗氮温度和渗氮的N2和H2的比例,通过正交试验分析这些参数对渗氮层耐磨性能的影响,结果表明最佳的耐磨性渗氮工艺为回火的温度600℃、渗氮温度460℃、N2：H2为1：5;耐磨性最差的渗氮工艺为回火的温度650℃、渗氮温度540℃、N2：H2为1：1。通过XRD分析表明白亮层的组织为以γ′相为主,并含一定量的α-Fe（N）相。这样的组织有很好的耐磨性,并且具有较小的的脆性。     

Effects of conventional and active screen plasma nitriding on properties of electroless Ni–B coating

Abstract

In the present study, the properties of nitrided electroless Ni–B coatings prepared by conventional plasma nitriding and active screen plasma nitriding were investigated. For this purpose, electroless Ni–B coatings were deposited from an alkaline bath on AISI 4140 substrates. Then, some of the prepared coatings were plasma nitrided by conventional method and the other ones by active screen method under the same conditions. Microstructure, morphology, microhardness and wear resistance of the coatings were evaluated. Based on the results, post-treatments change the amorphous as deposited coating structure to a crystalline one, which increases microhardness and wear resistance. Employing plasma nitriding treatment on the coatings results in higher microhardness and superior wear resistance than conventional heat treatment. The sputtering of iron atoms during plasma nitriding process can be the main reason for these results. In addition, active screen plasma nitriding demonstrates less surface roughness and superior wear resistance than conventional plasma nitriding.     

Microstructure and Wear Resistance of in situ Formed Duplex Coating Fabricated by Plasma Nitriding Ti Coated 2024 Al Alloy

In this study, plasma nitriding was carried out on pure titanium film coated 2024 Al alloy to improve its surface mechanical property. Ti film with the thickness of 3.0 mm was firstly fabricated by means of magnetron sputtering method. Then, the Ti coated specimen was subjected to plasma atmosphere comprising 40% N2e60% H2 at 430 C for 8 h. The microstructures of the nitrided specimens were characterized by X-ray diffraction and scanning electron microscopy. Microhardness tester and pin-on-disc tribometer were used to test the mechanical properties of the untreated and nitrided specimen. The results showed that the surface of the nitrided specimen was composed of three layers（i.e. the outside nitride Ti N0.3layer, the middle Al3 Ti layer and the inside Al18Ti2Mg3 layer）. The surface hardness and wear resistance of 2024 Al alloy were increased simultaneously by duplex treatment. The untreated specimen exhibited severe adhesive wear while the nitrided one behaved in middle abrasive wear.     

Surface Nanocrystallization of Commercial Pure Titanium Induced by SMAT and Its Properties

In this paper the preparation technique of surface nanocrystallization in commercial pure titanium was carried out by surface mechanical attrition treatment (SMAT). The mean grain size was calculated by using X-ray diffraction (XRD) and transmission electron microscope (TEM), and the results showed that the mean grain size of the surface was refined to nm Ievel after SMAT treatment. Nanocrystallized surface layers were formed after treated for 5, 15, 30 and 60 min. Microhardness experimental results implied the microhardness obviously increased on the surface layer and it also showed the variation of microhardness at the cross section. Corrosion test results showed the corrosion resistance of the surfaces in the original commercial pure titanium treated by SMAT was not improved in HCI solution. The corrosion micrographs were observed by scanning electron microscope (SEM).     

Microstructure and Tribological Properties of Plasma Nitriding Cast CoCrMo Alloy

A medical cast CoCrMo alloy was coated by plasma nitriding process to enhance the wear resistance.The microstructures,phases and micro-hardness of nitrided layers were investigated by atomic force microscopy(AFM),scanning electron microscopy(SEM),X-ray diffraction(XRD) and micro-hardness.Tribological properties were investigated on a pin-on-disc wear tester under 25% bovine serum solutions.The experimental results showed that plasma nitriding was a promising process to produce thick,hard and wear resistant layers on the surface of CoCrMo alloy.The harder CrN and Cr2N phases formed on the plasma nitrided layer with the compact nano-crystalline structure.Compared with the untreated sample,all nitrided samples showed the lower wear rates and higher wear resistance at different applied loads and nitriding temperatures.It was concluded that the improvement of wear resistance could be ascribed to the formation of thicker and harder nitrided layers with the specific microstructures on nitrided surfaces.     

钛合金表面氮化技术研究进展

本文概述了近年来为了提高钛及钛合金表面耐磨性在钛合金表面制备氮化钛膜层而采用的表面处理技术。从气体氮化、液体氮化以及离子氮化三方面讨论了每种工艺方法所获表面改性层的结构和性能特征及其适应范围。