Sliding wear resistance of TiCp reinforced titanium composite coating produced by laser cladding

Titanium metal matrix composite coatings (MMC) are considered to be important candidates for high wear resistance applications. Laser cladding (LC) by coaxial powder feeding is an advanced coating manufacturing process, which involves laser processing fine powders into components directly from computer aided design (CAD) model.In this study, the LC process was employed to fabricate TiC particle reinforced Ti6Al4V MMC coatings on Ti6Al4V hot rolled samples.The experimental results show that during LC process, TiC particles are partially dissolved into melted Ti-base alloy and precipitated in the form of TiC dendrites during cooling.Dry sliding wear properties of these MMC layers have been compared with substrate materials wear. The observed wear mechanisms are summarized and related to detailed microstructural observations. The layers have been found to show improved tribological properties connected with the TiC_p addition and the LC process parameters.     

The Tribological Performance of Surface Treated Ti6A14V as Sliding Against Si<Subscript>3</Subscript>N<Subscript>4</Subscript> Ball and 316L Stainless Steel Cylinder

Closed field unbalanced magnetron sputtering was used to deposit diamond-like carbon (Ti-C:H) coatings on Ti6Al4V alloy and gas nitrided Ti6Al4V alloy. Four different specimens were prepared, namely untreated Ti6Al4V alloy (Ti6Al4V), gas nitrided Ti6Al4V alloy (N-Ti6Al4V), Ti-C:H-coated Ti6Al4V alloy (Ti-C:H/Ti6Al4V) and Ti-C:H-coated gas nitrided Ti6Al4V alloy (Ti-C:H/N-Ti6Al4V). The tribological properties of the four specimens were evaluated using a reciprocating wear tester sliding against a Si₃N₄ ball (point contact mode) and 316L stainless steel cylinder (line contact mode). The wear tests were performed in a 0.89 wt.% NaCl solution. The results showed that the nitriding treatment increased the surface roughness and hardness of the Ti6Al4V alloy and improved the wear resistance as a result. In addition, the Ti-C:H coating also improved the tribological performance of Ti6Al4V. For example, compared to the untreated Ti6Al4V sample, the Ti-C:H coating reduced the wear depth and friction coefficient by 340 times and 10 times, respectively, in the point contact wear mode, and 151 times and 9 times, respectively, in the line contact wear mode. It is thus inferred that diamond-like carbon coatings are of significant benefit in extending the service life of artificial biomedical implants.     

Design and characterization of selective laser-melted Ti6Al4V–5Cu alloy for dental implants

Ti6Al4V–5Cu alloys have potential biomedical applications due to their adequate antibacterial properties. However, the wear and corrosion properties of these alloys are also crucial for dental implants. In the present study, Ti6Al4V–5Cu alloys were fabricated by selective laser melting (SLM). The microstructure and composition of Ti6Al4V–5Cu alloys by SLM were evaluated. The wear properties of the alloys in the simulated saliva environment and the atmospheric environment, as well as the electrochemical properties in the simulated saliva environment, were systematically investigated. The results showed that the crystal structure of Ti6Al4V–5Cu alloys was mainly composed of α-Ti and Ti₂Cu. In the SLM process, no preferred texture was observed due to the complex direction of the heat flux. The formation of Ti₂Cu can improve the strength of the material and make the titanium copper alloy have higher microhardness. Ti6Al4V–5Cu alloy showed a satisfactory wear resistance in both wear media. The addition of Cu reduced the second-phase content of the alloy. Meanwhile, the number of microcells was reduced, which was a positive factor to improve the corrosion resistance of the alloys.     

激光参数对Ti6Al4V钛合金激光冲击成形的影响

研究在Ti6Al4V合金激光冲击成形过程中,不同激光参数对板料弯曲角及表层硬度的影响。结果表明:当激光功率密度小于3GW/cm2时,弯曲角随着激光功率密度线性增加,激光功率密度超过3GW/cm2时,由于表面熔化现象的出现,弯曲角出现减小的趋势;板料弯曲角随冲击次数的增加也呈线性增长,但弯曲阻力的增加使得弯曲角的增长速度逐渐减慢;随着激光功率密度的增加,材料表面冲击区的硬度增高,表面硬化层的显微硬度最高达HV490,硬化层厚度约为1.0mm。     

Effects of hot isostatic pressing temperature on casting shrinkage densification and microstructure of Ti6Al4V alloy

The Ti6Al4V alloy castings were produced by the investment casting process, and the hot isostatic pressing(HIP) was used to remove shrinkage from castings. The processing pressure and holding time for HIP were 150 MPa and 20 min, respectively. Four different HIP temperatures were tested, including 750 ℃, 850 ℃, 920 ℃ and 950 ℃. To evaluate the effects of temperature on densification and microstructure of Ti6Al4V alloy treated by HIP, non-destructive testing and metallographic observation was performed. The experimental results show that the shrinkage was completely closed at 920 ℃ and 950 ℃. The densification of Ti6Al4V alloy increased as the HIP temperature increased below 920 ℃. The lamel ae were more uniform, the thickness of lamel ae was obviously broadened and the structure was coarsen. Besides, the Norton creep equation was used to simulate the effect of different temperatures on the densification of Ti6Al4V alloy during HIP. The simulation results were in good agreement with the experimental results. It was also found that 920 ℃ is a suitable temperature for HIP for Ti6Al4V alloy.     

Effects of Duplex Nitriding and TiN Coating Treatment on Wear Resistance,Corrosion Resistance and Biocompatibility of Ti6Al4V Alloy

Ti6Al4V alloy substrates were nitrided at 900 °C. TiN coatings were then deposited on the nitrided substrates using a closed-field unbalanced magnetron sputtering system. The microstructure, hardness and adhesion properties of the TiN-N-Ti6Al4V substrates were evaluated and compared with those of an untreated Ti6Al4V sample, a nitrided Ti6Al4V sample and a TiN-coated Ti6Al4V sample, respectively. The tribological properties of the various samples were investigated by means of reciprocating sliding wear tests performed in 0.9 wt.% NaCl solution against 316L, Si₃N₄ and Ti6Al4V balls, respectively. In addition, the corrosion resistance was evaluated using potentiodynamic polarization tests. Finally, the biocompatibility of the samples was investigated by observing the attachment and growth of purified mouse leukemic monocyte/macrophage cells (Raw 264.7) on the sample surface after culturing periods of 24, 72 and 120 h, respectively. Overall, the results showed that the duplex nitriding/TiN coating treatment significantly improved the tribological, anti-corrosion and biocompatibility properties of the original Ti6Al4V alloy.     

钛合金圆环工件表面合金化及其滚动摩擦性能研究

采用等离子表面合金化技术在Ti6Al4V合金圆环工件表面制备Mo渗镀改性层,将其与未渗Mo处理的Ti6Al4V合金在模拟实际工况条件下进行油润滑的滚动摩擦对比试验,比较二者的磨损情况,并分析磨损机理。结果表明,Ti6Al4V合金表面进行渗Mo处理后,形成了均匀、致密且高硬度的Mo基改性层。Ti6Al4V合金表面渗Mo后,硬度由渗层到基体呈梯度分布。滚动摩擦试验表明,渗Mo处理后表面无减摩效果,但磨损量大大减小,耐磨性得到有效改进。通过对磨损形貌的分析可知,表面渗Mo处理后磨损机理主要以磨粒磨损为主,而基材是磨粒磨损和粘着磨损。     

Ag和Ta离子双注入改善Ti6Al4V合金耐磨性能

采用Ag和Ta离子双注入对医用Ti6Al4V合金进行表面改性, 即以Ag离子1.0×10¹⁷ cm^-2 先注入、以Ta离子1.5×10¹⁷ cm^-2 后注入合金样品表面. 采用纳米力学探针研究离子注入前、后Ti6Al4V样品表面硬度随压入深度的变化, 利用多功能摩擦磨损试验机分析离子注入前、后样品的耐磨性, 利用XRD和XPS研究样品表面的物相组成和元素化合态. 结果表明, 离子注入后样品磨损量降低了77%. 耐磨损性能的明显改善归因于样品硬度增加, 磨损开始阶段保持低摩擦系数的时间较长和离子注入后合金固溶强化.     

Ti6Al4V合金干滑动磨损过程中摩擦层及摩擦氧化物的作用

目的分析Ti6Al4V合金在不同滑动速度下的干滑动磨损行为及磨损特征,研究钛合金的磨损机理,并探讨干滑动磨损过程中摩擦层及摩擦氧化物的作用。方法采用销盘式摩擦磨损试验机,对Ti6Al4V合金在不同滑动速度下进行干滑动磨损实验。采用磨损率和摩擦系数表征钛合金的磨损行为,采用SEM、EDS及XRD分析磨损表面及摩擦层的形貌及成分,采用数字显微硬度仪表征摩擦层的力学性能。结果滑动速度在0.5～4 m/s范围内变化,Ti6Al4V合金的磨损率发生显著变化,尤其是在高载条件下。0.5～1.5 m/s速度范围内,磨损率较低,2.68m/s速度下,磨损率达到最高值,4m/s速度下,磨损率达到最低值。0.75m/s速度下,粘着磨损和磨粒磨损为主要磨损机理,氧化磨损为次要磨损机理;2.68 m/s和4 m/s速度下的磨损机理分别为剥层磨损和氧化轻微磨损。2.68m/s速度下的高磨损率与硬度较低的无氧化物摩擦层对应,而4 m/s速度下的低磨损率与高硬度的多氧化物摩擦层对应。结论试验条件改变,Ti6Al4V合金的磨损行为及磨损机理发生变化。不同试验条件下的磨损行为与不同的摩擦层特征相对应,当摩擦层中包含一定量的摩擦氧化物时,这种陶瓷性的摩擦层具有比基体更高的硬度,能有效保护基体,降低磨损率。     

Ti6Al4V钛合金表面真空渗氧处理

目的在Ti6Al4V钛合金表层制备硬度高、耐磨性好的硬化层。方法结合真空技术,以高纯的O2为介质,在Ti6Al4V钛合金表面制备致密的渗氧硬化层,采用X衍射仪分析渗氧层的相组成,用金相显微镜观察渗氧层和磨痕组织,用显微硬度计测试渗氧层的显微硬度,用MM-U10A端面磨损试验机研究渗氧层的耐磨性。结果渗氧层物相主要由TiO_2、TiO、Ti_3Al及Al_2O_3组成,温度较低时,形成的渗氧层较薄,温度增加,渗氧层厚度迅速增加,硬度及耐磨性也随之增加。温度为760℃时,表面硬度为基体硬度的2.5倍以上,大于750HV,有效硬化层厚度达60μm以上,其磨损失重仅为未渗氧原样的1/4,表面磨痕细密,没有撕裂情况发生,渗氧层保持完整。温度继续增加,氧化物开始聚集长大,渗氧层组织开始变得疏松,硬度及耐磨性开始下降。结论 Ti6Al4V钛合金表面真空渗氧处理可显著提高其表面硬度,耐磨性改善明显。     

Sliding wear and friction behavior of ZA-27 alloy reinforced by Mn-containing intermetallic compounds

A ZA-27 alloy reinforced with M n-containing intermeta llic compounds was prepared and its tribological behaviors were investigated. By adding Mn, RE, Ti and B into ZA-27 alloy, the test alloy (ZMJ) was fabricated by sand casting. Microstructural analysis shows that considerable amount of Mn-containing intermetallic compounds such as Al5MnZn, Al9(MnZn)2 and Al65 Mn(RE)6Ti4Zn36 are formed. Compared to ZA-27, ZMJ shows better wear resistance, lower friction coefficient and lower temperature rise of worn surface under lubricated sliding condition. ZMJ also shows the lowest steady friction coefficient under dry friction condition. The wear resistance improvement of ZMJ is mainly attributed to the high hardness and good dispersion of these Mn-containing intermetallic compounds. It is indicated that the intermetallic compounds play a dominant role in reducing the sever adhesive and abrasive wear of the ZA-27 alloy.     

选区激光熔化制备多孔结构Ti6Al4V合金的力学性能

采用Simufact Additive软件，通过正交实验的方法，对激光选区融化（SLM）制备多孔结构Ti6Al4V合金的最优化工艺路线进行了模拟。结果表明，激光功率200 W，扫描速度1200 mm/s，光斑直径0.1 mm，粉末厚度0.03 mm为最佳加工参数。根据优化参数通过SLM加工制造了不同孔隙结构的Ti6Al4V样件，通过扫描电镜观察发现，在该工艺下加工出的多孔结构具有较好的保真度。通过压缩实验，比较分析实心及不同孔隙结构的抗压强度及弹性模量，得出复合结构作为种植体的结构模型可以更好满足种植体的力学性能要求。     

选区激光熔化成形Ti6Al4V合金摩擦磨损性能的各向异性

基于选区激光熔化技术制备了Ti6Al4V钛合金,研究了不同成形表面(XOY、XOZ)和不同载荷(20、40、60、80 N)对Ti6Al4V合金摩擦磨损性能的影响。通过摩擦系数(COF)结合磨损体积损失对不同成形面的摩擦磨损性能进行评估,采用光学显微镜(OM)、三维轮廓测量仪等设备对磨损轨道的形态和磨损机理进行表征。结果表明:相比XOZ面,XOY面在法向载荷为20N时其磨损体积减少了0.27×10-5 mm3,平均摩擦系数更小;而当载荷大于20N时,XOY面的磨损体积和平均摩擦系数均大于XOZ面。磨损轨道犁槽的深度和宽度随着载荷的增加而增加,犁槽呈现出明显的剥落行为,轨道处分布着块状的"粘合剂",发生着粘着磨损和氧化磨损。从摩擦系数、磨损体积、微观形态的角度定量反映出SLM成形Ti6Al4V合金的XOZ面比XOY面具备更优异的摩擦磨损性能,只有在低载荷下XOY面才表现出更加耐磨的特性。     

Microstructure characteristics of Ti3Al/TiC ceramic layer deposited by laser cladding

Al + TiC laser cladding coatings were prepared on Ti-6Al-4V alloy by CO₂ laser cladding technique. The microstructure, micro-hardness and phase constitutes of the laser cladding layer were investigated by means of scanning electron microscope (SEM), X-ray diffraction (XRD) and microsclermeter. The results indicated that the laser cladding layer solidified into the fine microstructure rapidly, and TiC hard phase was dispersived in the cladding layer. When the mass percent of TiC was 40%, the micro-hardness (1100HV_0.2-1250HV_0.2) of Al + TiC cladding layer was 3 times more than that of the Ti-6Al-4V alloy substrate (350-370HV_0.2). The cladding layer mainly consisted of α-Ti (Al), β-Al (Ti), Ti₃Al, TiAl, Al₃Ti and TiC phase. There phases were beneficial to improve the hardness and wear resistance of the cladding layer.     

Effects of Micro-Arc Oxidation of Ti6Al4V Alloy on Adhesion Property to Electroless Ni-P-ZrO2 Composite Platings and Their Wear Resistance

在Ti6Al4V合金微弧氧化膜表面制备Ni-P-ZrO2化学复合镀层,微弧氧化处理时间分别为15、30、60、90 min。采用扫描电镜/能谱仪、划痕试验、热震试验、显微硬度计和球盘式摩擦磨损试验机研究了微弧氧化膜结构对Ni-P-ZrO2化学复合镀层的结合性能与摩擦性能的影响。结果表明：随着微弧氧化时间的增加,复合镀层的结合性能显著提高,原因是微弧氧化膜的多孔性结构及其机械锁合效应。与Ti6Al4V合金相比,微弧氧化+化学复合镀处理后的试样硬度和耐磨性显著提高,Ti6Al4V合金表现为是严重的黏着磨损,而Ni-P-ZrO2复合镀层以磨砺磨损为主     

Ti6Al4V合金激光熔覆Co-Ti3SiC2复合涂层的组织和摩擦学性能

为改善Ti6Al4V合金的摩擦学性能,分别用纯Co、Co-2%Ti₃SiC₂、Co-5%Ti₃SiC₂、Co-8%Ti₃SiC₂混合粉末为原料,在Ti6Al4V合金表面激光熔覆制备复合涂层,利用X射线衍射仪(XRD)、扫描电镜(SEM)以及摩擦磨损试验机分析物相组成、显微组织结构以及在常温下的摩擦学性能。结果表明:所有复合涂层与基体结合良好,伴有少部分微孔。纯Co涂层的主要物相为γ-Co、CoTi、CoTi₂等,而Co-Ti₃SiC₂涂层物相包括γ-Co、CoTi、CoTi₂、TiC、Ti₅Si₃和残留的Ti₃SiC₂。涂层的硬度相对基体提高了1.90~2.15倍,而耐磨性能相应提高了3.02~5.44倍。     

Microstructures and Mechanical Properties of Ti6Al4V Parts Fabricated by Selective Laser Melting and Electron Beam Melting

This work compares two metal additive manufacturing processes, selective laser melting (SLM) and electron beam melting (EBM), based on microstructural and mechanical property evaluation of Ti6Al4V parts produced by these two processes. Tensile and fatigue bars conforming to ASTM standards were fabricated using Ti6Al4V ELI grade material. Microstructural evolution was studied using optical and scanning electron microscopy. Tensile and fatigue tests were carried out to understand mechanical properties and to correlate them with the corresponding microstructure. The results show differences in microstructural evolution between SLM and EBM processed Ti6Al4V and their influence on mechanical properties. The microstructure of SLM processed parts were composed of an α′ martensitic phase, whereas the EBM processed parts contain primarily α and a small amount of β phase. Consequently, there are differences in tensile and fatigue properties between SLM- and EBM-produced Ti6Al4V parts. The differences are related to the cooling rates experienced as a consequence of the processing conditions associated with SLM and EBM processes.     

激光表面纹理加工对Ti6Al4V空蚀性能的影响

采用激光表面改性的方法对Ti6Al4V合金进行纹理加工。采用表面粗糙度测试仪、接触角测量仪和X射线衍射仪对激光纹理加工试样的表面特性进行表征,采用磁致伸缩超声振动仪对试样的抗空蚀特性进行测试,采用光学显微镜和扫描电子显微镜对试样空蚀前、后的表面形貌进行观测。结果表明:经激光表面纹理加工,试样的硬度由337HV提高到550HV,水接触角增大10°;激光纹理加工试样的抗空蚀特性有所改善,特别是对于具有较小间距网格形状的表面纹理试样,其表面空蚀面积的比例小于抛光试样的1/10;激光纹理加工试样的抗空蚀特性的改善与硬度梯度效应、缓冲空泡运动和限域作用等效应相关。     

Improving tribological properties of Ti6Al4V alloy with duplex surface treatment

Ti-doped diamond like carbon films were deposited on both untreated and plasma nitrided Ti6Al4V alloy using Closed Field Unbalanced Magnetron Sputtering (CFUMBS) method and their tribological properties were evaluated by conducting sliding wear conditions. The influence of the nitrided layer on tribological behavior of Ti-DLC films was studied by means of XRD, SEM, scratch tester, microhardness tester and pin-on-disc tribotester. The microhardness results pointed out that the duplex treatment dramatically increased the surface hardness and reduced the plastic deformation of the alloy. Wear tests showed that Ti-DLC coatings on both untreated and nitrided surfaces caused a reduction in the coefficient of friction. The reason of the reduction in the coefficient of friction was found to be the formation of transfer film between the sliding surfaces. Wear rates demonstrated that wear resistance of duplex treated (Ti-DLC coating after nitriding) Ti6Al4V alloy was significantly improved.     

Ti6Al4V钛合金表面Zr-N合金化层的抗高温摩擦磨损性能

为了改善钛合金的高温耐磨性能,采用锆-氮离子共渗与异步渗(渗锆后再氮化处理)两种工艺技术分别在Ti6A14V钛合金表面制备致密的锆-氮合金化改性层,对比研究了合金化层的组织结构特征和高温摩擦磨损性能.结果表明,两种工艺制各的Zr-N合金层表面均由ZrN相组成,异步渗改性层的内层则包含较厚的Zr-Ti固溶体,两种等离子表面合金化层均使钛合金表面硬度显著提高.同样温度和处理时间条件下,异步渗合金化层的厚度约为锆-氮共渗合金化层厚度的6倍,且氮化物层也较厚,原因归于前者处理过程中Zr与Ti之间良好固溶特性的充分发挥及ZrN相的扩散障作用的有效抑制.300℃高温下球盘摩擦磨损试验结果表明,由于锆-氮共渗合金化层深度较小,因而改善钛合金基材耐磨性能的效果相对较低.锆-氮异步渗处理则使Ti6A14V钛合金耐磨性能显著提高,摩擦因数降低50％以上,比磨损率降低2个数量级,原因归于该类合金化层高的表面硬度、大的层深、良好的高温抗氧化性能及优异表面承载能力的有机匹配.