表面预处理对钛合金表面低温等离子体氮化的影响

为提高TC4钛合金表面摩擦学性能,探究酸洗及等离子体预处理对TC4钛合金表面低温等离子体氮化进程的影响。首先采用热丝增强等离子体氮化系统分别对表面酸洗及未酸洗TC4钛合金在氩气气氛下进行等离子体预处理,然后对各种表面预处理的TC4钛合金实施低温(500℃)等离子体氮化。采用扫描电子显微镜、能谱仪及X射线衍射仪分别分析了试样的截面形貌、氮势分布和物相组成;采用显微硬度计、摩擦磨损仪和轮廓仪测试氮化后TC4钛合金表面的显微硬度、磨痕曲线和摩擦系数,并计算了磨损量。结果表明:低温氮化后TC4钛合金基体组织形貌不变,表面获得厚度约10μm的氮化层。氮化后TC4钛合金的XRD衍射峰均向低角度偏移,表明形成含氮固溶体相。其中酸洗复合30 A等离子体预处理的TC4钛合金氮化后,XRD衍射峰向低角度偏移最明显,偏移量达0.2°。与基体相比,酸洗复合30 A等离子体预处理的TC4氮化表面显微硬度提高至691 HV,磨损量仅为基体的16%。酸洗复合等离子体预处理有效去除TC4钛合金表面氧化层、粗化表面,促进低温等离子体氮化进程,有利于含氮固溶体相形成,从而提高其表面摩擦学性能。     

航空钛合金表面激光气体氮化研究

利用激光气体氮化方法,实现了钛合金表面氮化处理。结果表明,当功率密度大于6．5×10^5W．cm-2时,生成物以TiN为主。由于Al的饱和蒸气压和蒸发速率均高于Ti,因此,在熔池表面形成贫铝层,促进了表面层Ti的氮化。热力学分析表明,激光熔池内生成TiN的反应较生成AIN的反应更具有热力学优势。     

GCr15钢表面脉冲激光氮化研究

利用Nd：YAG固体脉冲激光对GCr15钢样品表面进行了激光氮化处理,获得了高硬度、高耐磨损、表面致密均匀的氮化铁改性层,并对改性层进行了XRD谱分析和表面及剖面显微形貌分析、表面硬度及硬化深度和磨损率等的测量。同时对GCr15钢表面激光氮化机理进行了分析和研究。     

40CrNiMoA钢激光淬火+氮化复合处理

对40CrNiMoA钢分别经激光淬火、气体氮化、氮化-激光淬火复合处理及激光淬火-氮化复合处理的硬化层深度及其表面硬度分布进行了比较分析。结果表明，在激光淬火-氮化复合处理中，激光淬火可使随后氮化处理的表层硬度提高100-200HV，硬化层深度可成倍增加；在氮化-激光淬火复合处理中，激光淬火可使预先氮化处理的硬化层深度有大幅度的提高，而表层硬度变化不大。     

Mo的表面脉冲激光氮化

激光脉冲辐照置于氮气中的Ｍｏ使表面形成含γ－Ｍｏ２Ｎ的氮化层，激光使Ｍｏ表面熔化导致液相氮化反应，用ＳＥＭ、ＸＲＤ和ＡＵＧＥＲ谱分析表征了氮化层，激光在表层相起的加热和激波效应还有使表层微观组织致密的作用。     

金属钛激光气体氮化层组织及表面特征

采用连续波Nd-YAG激光在氮气环境中对金属钛进行激光气体氮化处理.利用SEM,XRD,XPS研究氮化层的显微组织、表面成分、结构.结果表明:通过激光气体氮化可以在金属钛表面得到表面相对平滑、无裂纹的氮化层;氮化层与基体材料之间为冶金结合.氮化层主要由枝晶状TiN组成,同时有TiNxOy,TiO2及TiC存在,外表面有C,O污染或吸附;TiN枝晶密度由表面沿深度方向下降.     

铀表面脉冲辉光等离子氮化初步研究

采用脉冲辉光等离子体离子氮化技术对贫铀表面进行了氮化处理,采用俄歇电子能谱(AES)对氮化层进行元素深度剖析,采用X射线衍射(XRD)、扫描电子显微镜(SEM)对氮化层组织结构进行了分析表征。结果表明:脉冲偏压-900 V,工作氮分压50 Pa、100 Pa,氮化时间2.5 h~4 h下在贫铀表面能获得约20μm厚的氮化层,氮化层为U2N3的单一立方结构且均匀致密,脉冲辉光等离子氮化技术能在贫铀表面实现氮化。     

几种难熔过渡金属的激光氮化

多脉冲激光辐射使置于氮气氛中的难熔过渡金属钛、钼和表面氮化，形成和组织致密的氮化层，用多种方法分析和表征了氮化层的化学成分和组织结构，激光的作用使得金属表面熔化和氮气激活，导致液相氮化反应，激光引起的加热熔化和激波效应同时使表层组织致密。     

球铁渗硫软氮化耐磨性研究

对球铁进行了渗硫软氮化试验，分析结果表明，在工件表面上形成一层很薄的多孔化合物层。文中除了找出最佳渗硫软氮化工艺方案外，对提高耐磨性机理进行了初步分析。     

NiTi合金低压等离子渗氮研究

采用低压等离子渗氮工艺对NiTi合金进行了渗氮处理.氮化处理后NiTi合金表面硬度升高.XRD测试结果表明在合金表面形成了一层TiN涂层,在TiN涂层下为Ni3Ti相.电化学腐蚀测试表明经氮化处理后合金的耐腐蚀能力大为提高.     

离子渗氮时Ti—6Al—4V表面粗糙度的影响

利用直流辉光放电化学处理方法对工业用Ｔｉ－６Ａｌ－４Ｖ合金进行离子渗氮处理，主要研究了不同温度，不同时间条件下钛合金表面粗糙度的变化情况。研究结果表明，高温离子渗氮在一定程度上使钛合金的表面粗糙义变差，其中离子渗氮温度影响比较明显。     

辉光等离子渗氮对纯钛铸件表面性能的影响

使用NH3在氮化炉中对纯钛铸件进行辉光等离子渗氮。分别应用X线衍射仪XRD、显微硬度计、扫描电镜、摩擦磨损实验及电化学实验研究等离子渗氮对纯钛铸件机械性能、摩擦学性能、耐腐蚀性的影响。铸造纯钛表面氮化处理后,颜色呈暗金黄色,表面由TiN、Ti2N相及氮在钛中的固溶体α-Ti(N)组成,显微硬度、耐磨性显著提高,在人工唾液中的耐腐蚀性亦明显提高。     

氮氩混合比对TA2真空氮化层结构与性能的影响

采用间歇式真空氮化技术对TA2钛合金进行渗氮处理。探究氮氩混合比对合金氮化层结构和性能的影响规律。结果表明:表面渗氮层主要由TiN和TiN0.3相组成,氮氩比越低其有效硬化层越厚,但会降低有效活性N原子的相对含量,不利于渗层的致密性。适当的氮氩混合比能在TA2表面形成氮化物,N原子有效地向纵深扩散,氮化物层与扩散层结合紧密,过渡良好,硬度梯度平缓;腐蚀电位随着氮氩比的增加呈现逐渐上升趋势,从氮氩比为1∶5时的-0.622V提升到氮氩比为5∶1时的-0.549V,腐蚀电流和腐蚀速率则呈现出逐渐降低的趋势。     

TC4钛合金低压真空氮化改性层的制备与性能

采用低压真空渗氮的方法,在TC4钛合金表面制备了与基体结合良好的改性层.通过金相观察、X射线衍射(XRD)和扫描电镜(SEM)分析了表面改性层的组织结构,并对改性层的显微硬度及耐磨性进了测试.结果表明:TC4钛合金经低压真空渗氮处理后,表面可获得由TiN和Ti2 AlN组成的氮化物改性层,组织均匀致密,氮化物颗粒细小,硬化层与基体结合良好,表面硬度为1100～1200HV,心部硬度为300～320HV,硬化层深度可达60～70μm,硬度梯度平缓,耐磨性优良.     

Laser Gas Nitriding of Ti-6Al-4V Part 2: Characteristics of Nitrided Layers

The characteristics of laser nitrided layers formed on Ti-6Al-4V are presented in this investigation. It has been determined that titanium nitride (TiN) is formed, which significantly increases the hardness of the nitrided surfaces. The amount of titanium nitride produced depends on the processing parameters such as laser pulse energy and nitrogen concentration. Nitrided layers are much smoother along the laser pass direction than perpendicular to this direction. The shrinkage effect in the laser melt zone produces surface residual tensile stresses in Ti-6Al-4V samples regardless of whether the processing environment is Ar, N₂, or a mixture of these gases. Pre-heating or stress relieving after laser nitriding significantly reduces the residual tensile stress level.     

不同温度下等离子渗氮后TC4钛合金的摩擦磨损性能EI北大核心CSCD

采用等离子渗氮技术提升TC4钛合金的耐磨性并探究最优渗氮温度。利用LDM 1-100型等离子渗氮设备,在650,700,750,800,850℃和900℃温度下对TC4钛合金进行渗氮处理,保温时间均为10 h。利用光学显微镜、扫描电子显微镜、白光三维形貌仪、X射线衍射仪和显微硬度计分别对不同温度渗氮试样的微观组织结构、表面形貌、表面粗糙度、相结构和硬度进行表征。利用CETR UMT-3型多功能摩擦磨损试验机测试等离子渗氮后TC4钛合金的摩擦学性能。结果表明:TC4钛合金表面显微硬度和粗糙度随温度升高而增大,在900℃渗氮后TC4钛合金表面显微硬度达到了1318HV 0.05,约为基体(360HV 0.05)的4倍。硬度的升高是由于渗氮后试样表面形成了硬质氮化物相(TiN和Ti2N相),且随着渗氮温度升高氮化物的含量增加。相较于低温渗氮(低于750℃)的试样,850℃和900℃渗氮试样的承载能力显著提升。与原始TC4试样相比,渗氮处理后试样的磨损体积显著降低。当渗氮温度为850℃时,试样磨损体积为未处理试样磨损体积的1.2%(1 N),3.0%(3 N)和62.2%(5 N),试样的耐磨性提升更为显著。     

Laser Gas Nitriding of Ti-6Al-4V Part 1: Optimization of the Process

A multi-variable test method, known as the Orthogonal Array, was used to optimize the parameters for the laser gas nitriding process (LGNP) to avoid surface cracking. Based on the fundamental requirement of a crack-free condition, the processing parameters were further optimized to improve the surface finish and to obtain a reasonable hardened depth. The effects of processing parameters have also been investigated with respect to the characteristics of the laser nitrided layer. Two types of lasers, i.e., CO₂ and Nd:YAG lasers were used. The CO₂ laser was operated in both the continuous as well as the pulse mode, while the Nd:YAG laser was used only in the pulse mode. A Nd:YAG laser in the pulse mode provided a better surface finish and lower cracking severity.     

Influence of Ultrafine‐Grained Layer on Gaseous Nitriding of Large‐Sized Titanium Plate

In this paper, mechanical shot blasting on a large sized titanium plate is conducted to induce severe plastic deformation, which generates an ultrafine‐grained surface layer. The effect of an ultrafine‐grained layer on nitriding is evaluated at nitriding temperatures from 600 to 850 °C. The structural phases and mechanical property improvements are investigated and compared to those of a coarse‐grained specimen by using X‐ray diffraction, scanning electron microscopy, transmission electron microscopy, and mechanical property measurements. The results indicate that an ultrafine‐grained layer enhances the nitriding kinetics and produces a thicker nitrided layer than that of a coarse‐grained plate at the same gaseous nitriding temperatures. The improved kinetics are attributed to a greater number of grain boundaries and defects introduced into the titanium plate surface by the mechanical shot blasting treatment. Meanwhile, the surface and cross‐sectional hardness values improve compared to the coarse‐grained plate due to the thicker nitrided layer resulting from deeper nitrogen diffusion.     

A new method for deposition of nano sized titanium nitride on steels

Active screen plasma nitriding is a new and common method for deposition of Iron nitride. Since techniques such as Chemical Vapor Deposition (CVD), Physical Vapor Deposition (PVD) and Plasma Assisted Chemical Vapor Deposition (PACVD) are usually applied in order to deposit the titanium nitride and each of these methods has its own problems, in this research active screen plasma nitriding method was introduced as a novel approach for deposition of nano sized titanium nitride. H11 tool steel samples were coated by plasma nitriding method at 550 °C for 5, 7.5 and 10 h, using three gas mixtures consisted of H₂/N₂ = 3, 1 and 1/3. Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD) and X-ray Photoelectron Spectroscopy (XPS) were employed to investigate the coating properties such as grain size, layer thickness and chemical composition. Results showed that the proportion of H₂ in the gas mixture was a crucial point in order to obtain a perfect coating. By increasing the coating time, the grain size and the layer thickness increased. XPS results showed that the coating was mainly consisted of TiN + TiN_0.1 together with a small amount of TiO₄.