激光熔凝高速火焰喷涂CoNiCrWC涂层组织与性能的研究

利用高速火焰喷涂在304不锈钢表面制备CoNiCrWC涂层,再利用5kW横流CO2激光对涂层熔凝。通过扫描电镜（SEM）观察熔凝层组织结构,测试并分析熔凝层显微硬度、耐磨性。实验结果表明,激光熔凝层与基材形成良好的冶金结合,熔凝层组织均匀：熔凝层显微硬度平均硬度为HV0．2964．314,明显高于基材硬度;在相同的奈件下,熔凝层的耐磨性比基体有了明显的提高。磨损体积减少了约89％。通过对磨损后的试样进行粗糙度观察后表明,涂层具有更平滑的表面。     

有效改善凸轮硬度和耐磨性的措施

介绍了几种能有效改善凸轮型面硬度和耐磨性的方法。凸轮磨损种类繁多,因根据具体情况选用适合的凸轮基材,并进行合理有效的热处理。合金涂层在不改变凸轮基材的情况下,能够有效提高凸轮的硬度和耐磨性。     

不锈钢的电火花表面强化

以1Cr18Ni9Ti不锈钢为基材,采用电火花堆焊技术,研究堆焊后微观组织和显微硬度的变化.结果表明,堆焊层晶粒比基体晶粒细小,显微硬度高于基体.电火花堆焊可以改善不锈钢的表面耐磨性.     

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。     

离子增强沉积Ti/Mo多层膜对钛合金微动疲劳行为的影响

为提高Ti6Al4V钛合金微动疲劳抗力,利用离子增强磁控溅射沉积技术制备了不同结构的Ti/Mo金属多层膜,评价了膜层的结合强度、韧性、硬度等力学性能和摩擦学性能,对优选出的Ti/Mo多层膜进行微动疲劳试验.研究结果表明:离子增强磁控溅射沉积的Ti/Mo金属多层膜膜层结晶细致,膜基结合强度高,有效地提高了钛合金基材的耐磨...     

C对多弧离子镀TiCN系超硬薄膜性能的影响

就C对TiCN系膜层的硬度、耐磨性、与Fe基材料的摩擦系数和粘附倾向的影响进行了试验研究。借助于SEM、AES、XRD、WDS等手段，对C在TiCN系膜层中的行为、作用进行了初步探讨。     

TiAlN膜层的研究进展

介绍了TiAlN基多层膜的发展及其它元素对薄膜性能的影响。其中薄膜多层化及添加其它元素都是获得具有优良的结合强度、硬度、耐磨性和高温抗氧化性能薄膜的重要手段 ,是今后TiAlN膜的重要发展方向     

不同激光熔覆材料涂层的耐磨性能比较

本文研究了宽带激光熔覆不同熔覆材料的复合涂层的耐磨性能。结果表明:Ni60B熔覆层的硬度高于40Cr基材的硬度,Ni60B+WC梯度复合涂层具有最高的硬度,对于提高零件的抗磨损性能比较有利;Ni60B熔覆层和Ni60B+WC熔覆层均适合修复轴类零件;三层梯度复合涂层磨痕宽度最小,具有最好的耐磨性。     

直流叠加脉冲法在铝合金阳极氧化中的应用

采用直流叠加脉冲法对ＺＬ１０８、ＬＣ２等高合金铝进行阳极氧化，并比较了氧化膜层的性能，分析了直流叠加脉冲法的优势。试验结果表明：该方法适用于所有常用铝合金的阳极氧化，所获得阳极膜不仅膜层致密、硬度高、耐磨性好，而且在生产上可提高生产率、节省能耗。     

H13热作模具钢稀土硼碳氮多元共渗

对H13热作模具钢稀土硼碳氮共渗工艺进行了研究，并对其共渗层的组织、硬度及耐磨性和抗氧化性进行了测试与分析，结果表明与碳氮硼共渗工艺相比，稀土硼碳氮共渗层的硬度、耐磨性和抗氧化性明显提高。稀土元素的渗入不仅提高了渗层的硬度、耐磨性和抗氧化性，并且使过渡层的硬度变化减缓，增强了基体与共渗层的结合，为共渗层提供强有力的支撑作用。     

Laser cladding of ti-6al-4v with bn for improved wear performance

Titanium and its alloys suffer from galling, seizing, ploughing and adhesion during sliding contacts. A laser-cladding method, to enhance the wear performance of titanium, was investigated. A 1.5 kW continuous-wave CO₂ gas laser was used to clad hexagonal BN powder with and without the addition of NiCrCoAlY on a Ti-6Al-4V alloy substrate. X-ray diffraction, scanning electron microscopy, optical metallography, and Vickers' micro-hardness tests were employed to characterize the clad layers. A pin-on-block reciprocating wear machine was used to evaluate the sliding wear characteristics of age-hardened, laser surface-melted and laser-clad Ti-6Al-4V alloys. Results indicated that the clad layers consisted of TiN, TiB₂, and various alloy phases. Claddings with excellent adhesion and thicknesses up to 600 μm, with a maximum hardness of 1600 HV, were obtained. Wear tests showed a substantial improvement (10–200 times) in wear resistance of claddings over age-hardened and surface-melted layers. The improved wear performance is attributed to the high hardness and low friction properties of clad layers.     

An investigation on sliding wear behavior of PVD coatings

Ti-6Al-4V alloy rubbing against aluminum-bronze 630 was evaluated in this work. High velocity oxygen fuel (HVOF) WC-10%Co-4%Cr thermal sprayed and TiN, CrN and DLC physical vapor deposition (PVD) coatings were applied to increase titanium substrate wear resistance. Pin-on-disk tests were performed with a normal force of 5 N and at a speed of 0.5 m/s, with a quantitative comparison between the five conditions studied. Results showed higher wear resistance for Ti-6Al-4V alloy DLC coated and aluminum-bronze 630 tribological pair and that the presence of graphite carbon structure acting as solid lubricant was the main wear preventing mechanism.     

Influence of Rapidly Solidified Structures on Wear Behavior of Ti-6AI-4V Laser Alloyed with TiC

In this paper the influence of rapidly solidified structures on the wear behavior of Ti-6Al-4V laser alloyed with TiC is studied by using an unlubricated sliding wear test. The results show that laser surface alloying with TiC can significantly increase wear resistance of Ti-6Al-4V. The wear of Ti-6Al-4V is characterized by adhesive de-lamination and melting showing a severe wear mechanism, while after alloying with TiC, it is changed into a mild wear mechanism characterized by a smooth, worn surface. This is attributed to directional fast-growing dendrites capped by a TiN/TiC film with high hardness and framed α marlensites obtained in rapid solidification.     

The Tribological Behavior of a Ti-46Al-2Cr-2Nb Alloy Under Liquid Paraffine Lubrication

The tribological behavior of a Ti-46Al-2Cr-2Nb alloy prepared by hot-pressed sintering was investigated under liquid paraffine lubrication against AISI 52100 steel ball in ambient environment and at varying loads and sliding speeds. For comparison, the tribological behavior of a common Ti-6Al-4V alloy was also examined under the same testing conditions. The worn surfaces of the two alloys were analyzed using a scanning electron microscope. The friction coefficient of the Ti-46Al-2Cr-2Nb alloy in the range of 0.13–0.18 was significantly lower than that of the Ti-6Al-4V alloy (0.4–0.5), but comparable to that under dry sliding, which indicated that TiAl intermetallics could be more effectively lubricated by liquid paraffine than titanium alloys. Applied load and sliding speed have little effect on the friction coefficient of the Ti-46Al-2Cr-2Nb alloy. The wear rate of the Ti-46Al-2Cr-2Nb alloy was about 45–120 times lower than that of Ti-6Al-4V alloy owing to Ti-6Al-4V alloy could not be lubricated effectively. The wear rate of the Ti-46Al-2Cr-2Nb alloy increased with increasing applied load, but decreased slightly at first and then increased with increasing sliding speed. The wear mechanism of the Ti-46Al-2Cr-2Nb intermetallics under liquid paraffine lubrication was dominated by main plowing and slight flaking-off, but that of the Ti-6Al-4V alloy was plastic deformation and severe delamination.     

不同摩擦副条件下Ti-6Al-4V合金的微磨粒磨损行为

采用TE66微磨粒磨损实验机对医用Ti-6Al-4V钛合金在不同摩擦副条件下的微磨粒磨损行为进行研究,考察滑行距离、载荷对其微磨粒磨损的影响,通过观察磨斑形貌,分析其磨损机制。研究结果表明:Ti-6Al-4V合金的磨损量随滑移距离和载荷增加而增加,磨损率则相反,并且硬度较高的Si3N4陶瓷球对合金造成的磨损量和磨损率均低于ZrO2陶瓷球;在不同摩擦副条件下,随着滑行距离和载荷的增加,Ti-6Al-4V合金的磨损机制均由三体磨损转变为二三体混合磨损,所不同的是与Si3N4陶瓷球对摩时合金的混合磨损区域要少于与ZrO2陶瓷球对摩时。     

Tribological Behaviour of Orthopaedic Ti-13Nb-13Zr and Ti-6Al-4V Alloys

The aim of this study is to compare the tribological behaviour of novel orthopaedic implant alloy Ti-13Nb-13Zr with that of the standard Ti-6Al-4V ELI alloy, available in four different microstructural conditions produced by variations in the heat treatments. The friction and wear tests were performed by using a block-on-disc tribometer in Ringer’s solution at ambient temperature with a normal load of 20–60 N and sliding speed of 0.26–1.0 m/s. It was found that variations in microstructures produced significant variations in the wear resistance of Ti-6Al-4V ELI alloy. The wear losses of materials solution treated (ST) above the β transus temperature are significantly lower compared with those of materials ST in the (α + β) phase field and are almost insensitive to applied load and sliding speed. Wear loss of the (α + β) ST Ti-6Al-4V ELI alloy continuously increased as applied load was increased and was highest at the highest sliding speed. The Ti-6Al-4V ELI alloy in all microstructural conditions possesses a much better wear resistance than cold-rolled Ti-13Nb-13Zr alloy. Friction results and morphology of worn surfaces showed that the observed behaviour is attributed to the predominant wear damage mechanism.     

A study of the cutting-induced heating effect on the machined surface in ultra-precision raster milling of 6061 Al alloy

Ti-6Al-4V alloy is an attractive material in many industries due to its unique and excellent combination of strength to weight ratio and their resistance to corrosion. However, because of its low thermal conductivity and high chemical reactivity, Ti-6Al-4V alloy is generally classified as a difficult-to-cut material that can be characterized by low productivity and rapid tool wear rate even at conventional cutting speeds. It is well known that tool wear has a strong relationship with the cutting forces and a sound knowledge about correlation between cutting forces variation and tool wear propagation is vital to monitor and optimize the automatic manufacturing process. In the present study, high-speed end-milling of Ti-6Al-4V alloy with uncoated cemented tungsten carbide tools under dry cutting conditions is experimentally investigated. The main objective of this work is to analyze the tool wear and the cutting forces variation during high-speed end-milling Ti-6Al-4V alloy. The experimental results show that the major tool wear mechanisms in high-speed end-milling Ti-6Al-4V alloy with uncoated cemented tungsten carbide tools are adhesion and diffusion at the crater wear along with adhesion and abrasion at the flank wear. The cutting force component in the negative y-direction is more dominant of the three components and displays significantly higher magnitudes than that of the other two components in x- and z-directions. The variation of cutting force component F _y has a positive correlation with the tool wear propagation, which can be used as a tool wear indicator during automatic manufacturing process.     

Corrosive Wear and Mechanical Properties of Ni/Al2O3 Micro- and Nanoparticulates-Reinforced Coatings on Ti-6Al-4V Alloy

Nanocomposite coatings can endow a plated surface with various properties such as wear resistance, high-temperature corrosion protection, oxidation resistance, and self-lubrication. This work studies the corrosion and corrosive wear resistance of electroplated nickel nanocomposite coatings on Ti-6Al-4V alloy in a Hank's solution, adding various concentrations of an Al₂O₃ powder in plating solution, with particle diameters of 20–30 nm and 1 μm for comparisons. The experimental results showed that the content of Al₂O₃ incorporated into the electroplated nickel composite coating increased with the concentration of Al₂O₃ powder in the electroplating solution, and increasing the surface hardness, corrosion, and corrosive wear resistance of electroplated nickel micro- and nanocomposite coatings caused smearing of the nodule boundary and elimination of voids in the deposits. The Al₂O₃ nanoparticulates were embedded and distributed more uniformly than the Al₂O₃ microparticulates in the nickel matrix after a heat treatment of 400°C, producing a more continuous and dense coated composite layer on the Ti-6Al-4V substrate. This phenomenon is responsible for the Ni/Al₂O₃ composite coating with superior surface hardness, providing high corrosion resistance and corrosive wear protection to the Ti-6Al-4V alloy substrate in Hank's solution.     

Comparative study on tribology and microhardness of laser synthesized Ti-Al2O3/Zn coatings on Ti-6Al-4V alloy

ABSTRACT

The study of laser cladding of 90Ti-10Al₂O₃, 90Ti-8Al₂O₃-2Zn and 90Ti-4Al₂O₃-6Zn coatings onto Ti-6Al-4V alloy, with intention to produce defect-less, high microhardness and wear resistant coating was carried out. The coatings were deposited onto Ti-6Al-4V alloy at 900 W laser power and 0.6 m/min laser scan speed. Microstructures and phase constituents of the developed coatings were investigated by using a scanning electron microscope (SEM) and X-ray diffractometer correspondingly. Vickers microhardness tester and pin-on-disk tribometer were employed to characterize microhardness and wear behaviour of the Ti-Al₂O₃/Zn coatings respectively. SEM was also used to examine the worn track. It was observed that 90Ti-10Al₂O₃ coating yielded optimal microhardness along with maximal wear resistance in comparison to the other coatings and Ti-6Al-4V alloy. It has been established that laser cladding of Ti-Al₂O₃ coating with Zn contents on Ti-6Al-4V alloy alleviates the formation of cracks, however, microhardness and wear properties are negatively affected.     

Tool wear in turning of titanium alloy after thermohydrogen treatment

The influence of hydrogen contents on the tool wear has been mainly focused on the flank wear of the common tool,and the influence of hydrogen contents on the rake crater wear(main wear type) of the tool,particularly for the fine granular material tool,has been less investigated comprehensively.In this paper,for the purpose of researching the influence of hydrogen contents on tool wear,the titanium alloy Ti-6Al-4V is hydrogenated at 800 ℃ by thermohydrogen treatment technology and the turning experiments are carried out by applying uncoated WC-Co cemented carbide tool.The three-dimensional video microscope is used to take photos and measure tool wear.The results show that both of crater wear depth(KT) and average flank wear width(VB) firstly decreases and then increases with the increasing of hydrogen content.The maximum reducing amplitude of KT and VB is about 50% and 55%,respectively.Under the given conditions,the optimum hydrogen content is 0.26%.It is considered that the reduction of cutting temperature is an important factor for improving tool wear after the Ti-6Al-4V alloy is properly hydrogenated.Furthermore,the reasons of hydrogen effect on the tool wear are chiefly attributed to comprehensive effect of hydrogen contents on microstructure,physical properties and dynamic mechanical properties of the Ti-6Al-4V alloy.The proposed research provides the basic data for evaluating the machinability of hydrogenation Ti-6Al-4V alloy,and promotes practical application of thermohydrogen treatment technology in titanium alloys.