TB8钛合金表面间歇式真空渗氮层的组织与性能

对TB8钛合金进行800℃间歇式真空渗氮6 h,研究了表面渗氮层的组织、硬度、耐磨性能及耐腐蚀性能.结果表明:TB8钛合金表面间歇式真空渗氮层主要由厚度60～80μm氮化物层和厚度110～130μm氮扩散区组成,表层物相包括TiN、TiN0.3、Ti2AlN及α-Ti,表层硬度为800～850 HV,由表层至心部硬度缓慢降低,心部基体的硬度为250～270 HV;在相同条件下,间歇式真空渗氮处理合金的磨损质量损失为未渗氮合金的1/12,表面形成了浅而窄的磨痕,耐磨性得到显著提高;间歇式真空渗氮处理合金在HF和HNO3混合溶液中的腐蚀速率仅为未渗氮合金的1/153,表面未见明显腐蚀坑,耐腐蚀性能得到明显提高.     

TC4钛合金低压渗氮研究

为了提高表面性能,对TC4钛合金进行低压渗氮处理。通过金相显微镜、X射线衍射(XRD)及显微硬度计分析了渗氮层的组织与硬度。结果表明,TC4钛合金经低压渗氮处理后,表面物相由Ti N、Ti2Al N、Ti3Al和α-Ti组成,渗氮温度较低时,渗氮层较薄,硬度较低,随渗氮温度升高,渗氮层厚度增加,表面硬度亦随之增加,温度为820℃时,表面硬度可达800~850 HV,硬化层深度为30μm~40μm,渗氮温度继续增加,渗氮层组织变得疏松,表面硬度开始下降。     

双辉渗镀TiN陶瓷层摩擦磨损性能的研究

采用一种新的制备TiN双层辉光渗金属技术，在钢铁材料表面直接复合而形成超硬耐磨TiN渗镀扩散陶瓷层。用Tapping AFM型原子力显微镜和LEC图像分析仪分析表面形貌；用GDS750型辉光放电光谱分析仪测定渗镀复合层试样成分；用Rigaku／max2500型X射线衍射仪（XRD）测定复合渗镀层的相结构；用WTM-1E可控气氛微型摩擦磨损试验仪对复合渗镀层的摩擦磨损性能进行研究。结果表明：这种制备TiN新工艺方法合成的渗镀TiN陶瓷层，其表面均匀致密，Ti和N原子由表层向内呈梯度分布，与一般表面沉积的TiN层不同，属于冶金扩散层结合；渗镀层厚度可达8μm以上，TiN层择优取向为（200）晶面；渗镀层硬度较高，达到HV0.1 2200，在干滑动摩擦磨损试验条件下具有较低的摩擦因数和优异的耐磨性能。     

TC4钛合金表面低压渗氮层的显微组织与耐磨性能

为了提高TC4钛合金的表面硬度及耐磨性,对其进行了820℃×10h的低压渗氮处理;通过X射线衍射仪、光学显微镜、扫描电子显微镜、显微硬度计及磨损试验机研究了表面渗氮层的显微组织与耐磨性能。结果表明:渗氮处理后,该钛合金表面形成了由表面氮化物层和次表面氮扩散层组成的渗氮层,其物相组成为TiN、Ti_2AlN和Ti_3Al;渗氮层的表面硬度为800~900HV,比基体的提高了近3倍,截面硬度随着深度的增加而下降;在相同条件下,渗氮后试样的磨损质量损失比未经渗氮处理的小,且随载荷的增加磨损质量损失增加更缓慢,耐磨性得到了极大的改善。     

17-4PH不锈钢表面TiO_2膜及其多层膜的结构与性能

利用非平衡磁控溅射技术在17-4PH不锈钢表面分别制备了TiO_2膜、TiO_2/Ti多层膜及TiO_2/Ti/TiN/Ti多层膜,采用XRD、表面轮廓仪、显微硬度仪、摩擦磨损试验机和水蒸气疲劳腐蚀试验设备研究了薄膜的物相、显微硬度、耐磨性和耐疲劳腐蚀性能。结果表明:具有表面薄膜17-4PH不锈钢的硬度、耐磨性和耐腐蚀性能均有较大提高;与TiO_2膜和TiO_2/Ti/TiN/Ti多层膜相比,TiO_2/Ti多层膜耐磨性能最好,较基体的提高了20倍以上,同时其耐疲劳腐蚀性能也最好。     

C离子注入对硬质合金刀具TiN涂层性能的影响

在硬质合金刀具上沉积了PVD—TiN涂层,并采用C离子注入技术对其进行表面改性处理。对涂层截面的微观形貌、显微硬度以及与基体附着力的测试结果表明,C离子注入可使TiN涂层的显微组织细密均匀化,并能明显提高涂层的显微硬度以及与基体的附着力。     

GCr15钢等离子体源离子注入表面改性

用等离子体源离子注入技术对GCr15钢进行了氮离子注入,对注入层的成分进行了俄歇剖面分析,对注入层的显微硬度和摩擦性能进行了测试,对摩擦磨损表面进行了扫描电镜分析,研究结果表明;注入层的硬度和耐磨性均获得了明显的提高。     

钛合金人工心脏瓣膜瓣环表面TiN/Ti多层膜的制备与性能

为了提高钛合金人工心脏瓣膜瓣环TiO_2表面改性层的性能,利用非平衡磁控溅射技术在人工心脏瓣膜瓣环表面制备了具有不同调制周期(44,70,100 nm)的TiN/Ti多层膜过渡层;采用XRD、SEM、显微硬度计及摩擦磨损试验机研究了薄膜的物相组成、横截面形貌、硬度和耐磨性。结果表明:TiN/Ti多层膜由Ti和TiN相组成,当调制周期为100 nm时,TiN/Ti薄膜呈现明显的多层结构,具有高硬度和良好耐磨性;人工心脏瓣膜瓣环表面各个位置TiN/Ti多层膜的相结构及性能相同,可望应用于人工心脏瓣膜瓣环的TiO_2表面改性层的过渡层。     

精密铸造零件表面渗氮的DOE分析

目前,渗氮工艺因其使精密铸造零件具有较好的耐磨性而被广泛应用于汽车领域。由于铸造零件本身的成型工艺致使零件表面粗糙度不良,零件经过渗氮热处理后出现表面硬度值偏低的情况,难以满足客户要求。通过试验验证的方法,首先解决了在表面粗糙度不良的情况下如何准确测量维氏硬度的问题;其次通过对渗氮层微观组织分析,确认表面硬度不良的主要原因;最后运用试验设计(DOE)方法,确认了产生白亮层疏松和扩散层氧化的主要因子,通过优化工艺提高了渗氮后零件的表面硬度。     

气体氮化工艺探究

经气体渗氮后,专用渗氮用钢表面硬度可达50N载荷下维氏硬度1000HV（相当于洛氏硬度70HRC左右）,而且在600℃的温度下仍能保持高硬度和耐磨性。由于渗氮后零件表面可以得到更大的残余压应力,渗氮后疲劳强度也可大幅度提高。渗氮零件由于工艺温度较低（一般在480～600℃）,而且升温和降温的速度都较慢,处理过程中零件心部没有相变,因此变形很小。又由于渗氮变形主要是由渗氮层体积胀大引起,所以规律性强,     

Effect of laser power on the microstructure and mechanical properties of TiN/Ti3Al composite coatings on Ti6Al4V

Laser nitriding is one of the effective techniques to improve the surface properties of titanium alloys and has potential application in the life extension of last-stage steam turbine blades. However, cracking of surface coating is a common problem due to heat concentration in laser nitriding process. Conventionally, the cracks can be avoided through heat treatment, which may have an important influence on the mechanical properties of coating. Crack-free TiN/Ti3Al IMC coatings on Ti6Al4V are prepared by plasma spraying and laser nitriding. The microstructures, phase constitutes and compositions of the coating are observed and analyzed with scanning electron microscopy(SEM), X-ray diffraction(XRD) and X-ray energy-dispersive spectroscopy(EDS). Microhardness, elastic modulus, fracture toughness of the coating are measured. The results show that the crackand pore-free IMC coatings can be made through the proposed method; with increasing laser power, the amount and density of TiN phase in the coating first increased and then decreased, leading to the similar trend of microhardness and elastic modulus and the reverse trend of fracture toughness of the coating. Both the average microhardness and elastic modulus of the coating increase three times higher than those of the substrate. The volume fraction of the TiN reinforced phase in composite can be controlled by varying the laser power and the cracking problem in laser nitriding process is successfully solved.     

Multi-pass scratch test behavior of modified layer formed during plasma nitriding

316L stainless steel and Ti6Al4V alloy were plasma nitrided at different treatment parameters, and the wear behaviors of the modified layers formed on the surface during nitriding were investigated by multi-pass scratch test. Phase structure and cross-sections of modified layers were also examined with XRD and SEM. While a single modified layer formed on surface of the 316L stainless steel, both modified and diffusion layers were observed on the surface of the Ti6Al4V alloy after nitriding. As a result, it was observed that phase structure and thickness for modified layers of 316L stainless steel and Ti6Al4V alloy, respectively, were the significant parameters for friction coefficient and wear rate. In addition, diffusion layer formed during the nitriding process caused on increase of wear resistance of Ti6Al4V alloy by supporting the modified layer on the surface.     

物理气相沉积TiN薄膜疲劳磨损形貌的AFM观测

采用物理气相沉积工艺在高速钢表面沉积TiN薄膜,研究了TiN薄膜的疲劳磨损过程。采用原子力显微镜(AFM)观测分析了表面疲劳点蚀的形貌特征。试验结果表明:较厚TiN薄膜具有较低的疲劳磨损寿命,而较薄的TiN膜层具有较高的疲劳磨损寿命。在试验的初始阶段,磨损轨迹上都出现大量显微凹坑,AFM观测分析可知显微凹坑起源于薄膜表面,呈菱形状。随试验的进行,较薄的TiN薄膜出现典型的疲劳麻坑,而较厚的TiN薄膜在薄膜与基体的界面处形成疲劳裂纹,并出现严重的剥层和断裂。     

Micro-scale abrasive wear testing of duplex and non-duplex (single-layered) PVD (Ti,Al)N, TiN and Cr–N coatings

A micro-scale abrasive wear test, based on ball-cratering, has been used to evaluate the wear resistance of duplex and non-duplex (Ti,Al)N, TiN and Cr–N coatings. The term duplex is used here when plasma nitriding is followed by PVD coating. Coatings without the plasma nitriding stage are termed single-layered. Coating properties were evaluated by surface profilometry, hardness and scratch testing. All duplex coatings showed higher micro-abrasive wear resistance than their single-layered counterparts, with the duplex (Ti,Al)N coating achieving the best performance. After a certain number of ball revolutions, the coating material became worn through, exposing the substrate material. After this point, the presence of a hard nitrided case diminished the scratching action of the SiC abrasive particles. The experimental results also indicate that the choice of the PVD coating plays an important role in improving the micro-abrasive wear resistance. Apart from single-layered and duplex Cr–N coatings, all the other coating systems provided a higher micro-abrasive wear resistance than the uncoated substrate (hardened AISI H13 steel). The poor abrasive wear resistance recorded for the single-layered and duplex Cr–N coatings could be attributed to the hardness of the Cr–N being much lower than that of the SiC abrasive particles, which caused tearing of the coating with subsequent delamination. The wear pattern observed was found to change from surfaces characterised by grooves (uncoated substrate, single-layered TiN and Cr–N systems and duplex Cr–N system) to surfaces which exhibited multiply indented surfaces (single-layered and duplex (Ti,Al)N systems), indicating a transition between wear mechanisms. This transition was found to be dependent on the ratio between the hardness of the SiC abrasive particles and surface (coating) or subsurface hardness. By decreasing this ratio, the ability of the SiC abrasive particles to scratch the composite surface was reduced and the resistance to micro-scale abrasion was improved.     

不同涂层刀具切削淬硬H13钢加工性能研究

为了研究不同涂层刀具切削淬硬H13钢的切削性能,进行了多层Ti化合物涂层、TiAlN涂层以及MTTiCN厚Al_2O_3TiN涂层材料刀具车削加工淬硬H13钢试验,分析了不同的涂层材料刀具与切削力、切削温度、涂层刀具磨损以及刀具寿命的关系。研究得出:多层Ti化合物涂层刀具受到三个方向的力都大于其它两种涂层的刀具,而且切削温度最高;用TiAlN涂层刀具切削时温度最低;切削过程中三种刀具后刀面磨损程度不同,发现多层Ti化合物涂层刀具磨损最为严重,寿命最短;MT-TiCN厚Al_2O_3Ti N涂层材料刀具比多层Ti化合物涂层刀具寿命长30%;TiAlN涂层刀具的切削寿命最长比多层Ti化合物涂层刀具寿命长45%。     

Vacuum Tribological Properties of Titanium Enhanced via Ultrasonic Surface Rolling Processing Pretreatment and Plasma Nitriding

For the purpose of enhancing the vacuum friction-reducing and antiwear performance of UNS R50400 Ti, ultrasonic surface rolling processing (USRP) has been introduced as pretreatment of plasma nitriding (PN). Various nitriding temperatures from 650 to 950°C have been adopted to investigate the effects of USRP pretreatment on plasma nitriding of Ti. The results of experiments show that the friction-reducing and antiwear performance are enhanced by USRP pretreatment when the PN temperature is below 750°C, resulting from the formation of thicker and harder nitriding layer with a reasonable gradient structure. Nevertheless, USRP pretreatment results in a rough surface and a large-sized columnar crystal gradient structure when the PN temperature is above 750°C, leading to poor vacuum tribological performance. In aggregate, USRP pretreatment is an effective pretreatment to decrease the optimized plasma-nitriding temperature from 850 to 750°C.     

高频感应加热膏剂法制备渗铬层的组织与性能

利用高频感应加热膏剂法在Ti6Al4V合金表面制备了渗铬层,对渗铬层的厚度、显微组织、化学成分、硬度、结合强度以及摩擦学性能进行了研究。结果表明:渗铬层厚度可达25μm以上;渗铬后在合金表面形成了由α+β、CrVO3、(Ti0.88Cr0.12)2O3和TiN相组成的渗铬层;渗铬层的化学成分呈梯度分布,距渗铬层表面25μm处的硬度可达850HV,渗铬层与基体实现了冶金结合,明显提高了基体的摩擦学性能。     

Ti添加方式对表面无立方相层梯度硬质合金的影响

表面无立方相层梯度硬质合金是一种非常好的涂层刀具基体材料,近年来越来越受到重视。本文主要研究了Ti添加方式对于表面无立方相层梯度硬质合金的影响。研究发现,相对于添加TiN、TiC,添加TiCN得到的表面无立方相层梯度硬质合金综合性能更好。     

Tribological performance evaluation of (1 1 1) preferred oriented TiN duplex coatings

The duplex surface coating of hot work tool steel, which comprises nitriding of a substrate and coating of a TiN layer, has been the subject of a series of studies as a potential surface modification for tools and machine parts. Through sliding experiment against an aluminum alloy without lubrication, it was shown on a wear map that there are two domains depending on sliding conditions: the wear domain and the transfer domain. In this study, focusing on the improvement in the tribological properties of the duplex coating in terms of the wear domain, the effects of film characteristics on film resistance to erosion wear and film life were investigated. Two kinds of duplex coatings with different film characteristics were prepared by hollow cathode discharge ion plating: a newly developed TiN film with a strong (1 1 1) orientation and an ordinary TiN film with (1 1 1) and (2 0 0) orientations. The erosion wear rate of duplex coating was evaluated by a micro slurry jet erosion test. Film life was evaluated by a sliding test against an aluminum alloy as in previous experiments. It was revealed that the duplex coating with the newly developed TiN film (N-coating) shows higher erosion resistance than previously reported duplex coating (C-coating). From the sliding test, it was also revealed that the N-coating whose XRD intensity ratio of (1 1 1) to (2 0 0) is over 100 shows a wear mode with only chipping, with no scratching, which shortens film life. The film life of N-coating increases about twice as long as C-coating, which has shown higher performance than a conventional duplex coating. Possible mechanisms of the improvement in the tribological properties with N-coating are discussed.     

TiN/Ti涂层在波箔轴承中的摩擦磨损性能

采用真空离子镀的方法在304不锈钢基体上喷涂厚度为3μm的TiN/Ti薄层,利用硬度计、三维形貌仪、划痕试验仪对涂层基本力学性能进行分析,通过球盘试验机分析涂层试样的摩擦磨损性能,根据波箔轴承性能测试实验台的测试结果:研究TiN/Ti涂层对基体表面耐磨减摩性能的影响。研究结果表明:TiN涂层硬度可达HV1500,是基材硬度的5.5倍;TiN/Ti涂层平均摩擦因数为0.23,相对不锈钢304基材的平均摩擦因数0.71,降低了68%,磨损量也仅为基材的18.75%;GCr15与PTFE对磨的最大摩擦力矩可达2.4 N·mm,而TiN/Ti与PTFE对磨的最大摩擦力矩仅为1 N·mm,仅为GCr15的41.7%。TiN/Ti涂层表现出了优异的承载能力和耐磨减摩性能。