钛合金表面激光熔覆Ti/Ni+Si3N4/ZrO2复合涂层组织与性能研究

目的 提高TA15合金的表面硬度,改善其耐磨性能.方法 以Ti/Ni+Si3 N4/ZrO2混合粉末为原料,利用激光熔覆技术,在TA15钛合金表面制备出以ZrO2颗粒和原位生成Ti5 Si3、TiN为增强相,以金属化合物TiNi、Ti2 Ni为基体的复合涂层.采用X射线衍射仪、扫描电镜及能谱仪等手段分析激光熔覆涂层的显微组织及磨损表面,通过硬度测试、摩擦磨损实验,对熔覆层的显微硬度和耐磨性进行评估.结果 熔覆层与基体形成了良好的冶金结合,熔覆层组织中TiNi和Ti2 Ni金属化合物基体上弥散分布着Ti5 Si3、TiN树枝晶和ZrO2颗粒;与不含ZrO2熔覆层相比,含有ZrO2熔覆层组织的晶粒得到细化;熔覆层中原位生成的TiN桥接在裂纹上,具有增韧的作用;熔覆层的显微硬度分布在835~1050 HV区间内,约为基体硬度的3倍左右;在干滑动摩擦磨损下,熔覆层的磨损量约为钛合金基体磨损量的1/6,其主要磨损机制为磨粒磨损和黏着磨损.结论 熔覆层中高硬度、耐磨陶瓷相和高韧性相的共同配合,显著提高了钛合金表面的硬度和耐磨性.     

Effect of TiN/Ti composite coating and shot peening on fretting fatigue behavior of TC17 alloy at 350 °C

A TiN/Ti composite coating has been prepared on a TC17 titanium alloy substrate by an ion-assisted arc deposition (IAAD) technique with a view to improving the fretting fatigue resistance of the titanium alloy at 350 °C. The composition distribution, bonding strength, micro-hardness, ductility, tribological properties, and fretting fatigue resistance at elevated temperature of the coating have been investigated. The results indicate that the IAAD technique can be used to prepare a TiN/Ti composite coating with high hardness, good ductility, excellent bonding strength, and high load-bearing capability. The TiN/Ti composite coatings can improve the resistance to wear and fretting fatigue of the Ti alloy, as manifested in its excellent tribological behavior at 350 °C. However, the fretting fatigue resistance of the titanium alloy treated by shot peening (SP) combined with IAAD TiN/Ti coating post-treatment was lower than that by IAAD TiN/Ti coating or SP alone, because the compressive residual stress induced by SP was significantly relaxed during coating process and the coating easily cracked and broke off.     

钛合金表面百微米级Ti/TiN多层复合涂层性能研究

目的提高TiN硬质涂层的厚度及各项力学性能。方法采用等离子增强PVD技术在钛合金(TC4)基体表面制备多层复合Ti/TiN涂层,对涂层进行扫描电镜(SEM)分析,采用划痕法表征涂层的结合强度,用维氏显微硬度计测试涂层的显微硬度,利用销盘式摩擦磨损试验仪评价涂层的摩擦磨损性能。结果制备的多层复合Ti/TiN涂层厚度最高可达100μm,且未发生剥落等失效,结合强度相对于单层TiN提高了近3倍。由于Ti、TiN的多层复合调制作用,制备的Ti/TiN显微硬度测试表明复合涂层的显微硬度高达2700 HV0.025,同时,涂层在原有耐磨性能优良的基础上具备自润滑减摩作用,经过近20 000 m的磨损测试,复合涂层的摩擦系数低至0.25左右,且未完全失效。结论多层复合结构能够有效提高TiN硬质涂层的厚度,制备的Ti/TiN多层复合涂层的各项力学性能显著提高。     

原位合成TiN增强Ni基复合涂层的组织与性能

以Ti,BN和Ni粉为原料,在Q345D钢表面采用氩弧熔敷技术制备了TiN增强Ni基复合涂层.利用扫面电镜(SEM)和X射线衍射仪(XRD)对复合涂层的显微组织进行了分析,TiN颗粒呈球形、不规则椭球状和枝晶状,并对其形貌特征进行了解释.利用显微硬度计和摩擦磨损试验机,对复合涂层的相关性能进行了测试和分析.涂层表面平均...     

不同压力对 TC4 钛合金真空脉冲渗氮的影响

目的采用不同压力对TC4钛合金进行真空脉冲渗氮处理,提高其表面硬度及耐磨性。方法通过金相显微镜、X射线衍射仪、显微硬度计及耐磨试验机分析渗氮硬化层的组织与性能。结果 TC4钛合金经过真空气体渗氮处理后,形成了由Ti N,Ti2Al N和钛铝金属间化合物Ti3Al组成的复合改性层。渗氮压力太低,表面氮化物数量较少,氮化物层较薄;随渗氮压力的增大,表面氮化物数量增多,表面硬度及耐磨性增加。压力为0.015 MPa时,氮化物层表面硬度最大,表面硬度为1100~1200HV,有效硬化层深度为50~60μm。渗氮压力继续增加,表层组织变得疏松,表面硬度及耐磨性开始降低。结论选择合适的渗氮压力和表面氮浓度进行真空脉冲渗氮,可以提高钛合金表面硬度,改善耐磨性。     

TC4钛合金表面激光熔覆WC增强镍基复合涂层的组织及耐磨性

为提高TC4钛合金的耐磨性,利用激光熔覆技术(laser cladding,LC)在TC4钛合金表面制备Ni60+50%WC(体积分数)和deloro22(d22)粉末打底+(Ni60+50%WC)2种耐磨复合涂层。采用扫描电子显微镜(SEM)、能谱仪(EDS)以及X射线衍射仪(XRD)来表征涂层的微观结构和物相组成;使用HV-1000显微维氏硬度计、HRS-2M型高速往复摩擦磨损试验机和WDW-100D电子万能试验机来分析涂层的性能。结果表明:2种涂层均由W₂C、TiC、Ni₁₇W₃、Ni₃Ti和Ti_xW_1-x相组成,2种涂层不仅与基体呈现出优异的冶金结合,而且组织均匀致密,没有裂纹瑕疵;由于涂层中存在着原位合成的硬质相和细晶强化共同作用使得涂层硬度显著提高,约为TC4基体的2.82倍;2种涂层的摩擦系数(COF)和磨损量都远低于TC4钛合金基体;Ni60+50%WC复合涂层和d22粉末打底+(Ni60+50%WC)复合涂层的抗剪切结合强度分别为188....     

激光熔敷Ti5Si3／NiTi金属间化合物复合材料涂层组织与耐磨性

以Ti14Si6Ni80合金粉末为原料，利用激光熔敷技术在BT9钛合金表面制得以金属硅化物Ti5Si3为增强相、以金属间化合物NiTi为基体的快速凝固金属间化合物复合材料涂层，分析了该涂层的显微组织，在室温干滑动磨损条件下测试了其耐磨性。研究结果表明，涂层硬度高、组织致密、与基材之间为完全冶金结合，在干滑动磨损试验条件下具有较好的耐磨性。涂层具有优异耐磨性的主要原因是作为耐磨增强相的金属硅化物Ti5Si3具有高硬高耐磨的特性，在涂层中起到了抗磨骨干作用，同时作为涂层基体的金属间化合物NiTi由于具有极强的原子结合键及应力诱发马氏体相变特性，本身具有优异的耐磨性，在摩擦过程中对耐磨增强相Ti5Si3起到了强力支撑作用。     

Structure and hardness of titanium surfaces carburized by pulsed laser melting with graphite addition

Titanium foils coated with graphite films 20 μm thick were irradiated by means of a pulsed Nd-YAG in order to harden this metal by surface melting and alloying. The relationships between irradiation parameters, microstructure and hardness of the synthesized composite coatings were determined. Four relevant parameters were defined as governing the irradiation processes. The parametric working field of the laser source was investigated next to its periphery. The influences of the relevant irradiation parameters on the microstructure and hardness of the melted zone were deduced from the metallographic analyses and Vickers micro-indentation tests of the cross sections of this composite zone. Such a zone was constituted always with hard titanium carbide and ductile metallic titanium, some times with the presence of lubricating graphite inclusions. The main advantage of such a surface treatment of titanium is to synthesize, under clearly defined irradiation conditions, a self-lubricating composite coating that resists abrasive or adhesive wear.     

激光熔覆 CBN 膜层的形态特征及性能研究

目的提高钛合金的表面硬度和耐磨性能。方法采用激光熔覆工艺,在TC11钛合金表面制备80%CBN+20%Ti(均为质量分数)熔覆层,分析熔覆层的显微组织、硬度和耐磨性能。结果熔覆层的显微组织沿层深方向分为熔覆区、结合区和过渡区三个区域,区域之间没有明显的裂纹和断层。CBN膜层的显微硬度最高达到950HV0.2,耐磨性比纯Ti熔覆层提高了近14倍。结论在钛合金表面激光熔覆CBN抗磨涂层,不仅耐磨损性能良好,而且表面硬度得到了有效提高。     

钛合金表面氩弧熔覆TiC增强复合涂层组织与性能分析

把石墨粉末预涂在钛合金表面上,利用氩弧熔覆技术成功制备出原位自生TiC增强的金属基复合涂层。利用扫描电镜、X射线衍射仪和能谱仪分析了熔覆涂层的显微组织,探讨了增强相TiC的生成机制;利用显微硬度仪测试了复合涂层的显微硬度并用磨损试验机考察了其在室温干滑动磨损条件下的耐磨性能。结果表明,氩弧熔覆涂层组织均匀致密,原位自生TiC呈树枝晶和细碎的条状均匀地分布于整个涂层中;由TiC增强的复合涂层明显地改善了钛合金的表面硬度．平均硬度约为700HV0．2且沿层深方向呈梯度分布;涂层在室温干滑动磨损条件下的耐磨性明显优于基体,约为钛合金的10．5倍．     

钛合金表面激光熔覆 h-BN 固体润滑涂层

目的优化钛合金激光熔覆固体润滑涂层的熔覆工艺参数,提高钛合金表面耐磨性能。方法采用Nd∶YAG激光器,分别在高功率和低功率条件下,在TC4钛合金表面制备h-BN固体自润滑涂层。观察分析熔覆陶瓷层的宏观形貌、物相组成、显微组织和硬度,采用摩擦磨损试验仪对熔覆层的摩擦学性能进行研究。结果低激光功率下,熔覆材料上浮流失严重,熔覆层的相成分主要是Ti N,Ti B,Ti B2等硬质相,硬度较高,存在裂纹。高激光功率下,基材的熔化稀释较好地抑制了润滑相h-BN的上浮,减少了溅射损失,发生了包晶反应,生成了单质金属Ti,熔覆层硬度低,但摩擦磨损试验表明,涂层中润滑相h-BN含量的增加使得形成了更好的润滑膜,降低了摩擦系数。结论在输出电流400 A,脉宽5 ms,频率12Hz,扫描速度120 mm/min,搭接率50%~60%的条件下进行激光熔覆,所得熔覆层的表面状态平整,耐摩擦性能最好。     

Improvement of the wear resistance of titanium alloyed with boron nitride by electron beam irradiation

Surface alloying of commercially pure titanium was carried out with an electron beam (EB) apparatus using a boron nitride powder which was previously deposited on its surface by Atmospheric Plasma Spraying (APS) in order to produce a composite layer with high wear resistance.Electron beam surface alloying is an important surface engineering routine that involves melting of a pre-deposited layer or concomitantly added alloying elements/compounds with a part of the underlying substrate by direct energy electron beam irradiation to form an alloyed zone characterized by a novel microstructure and composition.The present study is concerned with the influences of EB-remelting process on the wear resistance of the alloyed titanium material. The microstructure, corrosion resistance and phase analysis were also examined. Scanning electron microscopy (SEM), light microscopy (LM) and X-ray Diffraction (XRD) were performed to characterize the phase modification and morphology after the EB treatment. The sliding wear as well as the hardness of the remelted material was significantly improved (in comparison with pure Ti) through this alloying technique. The corrosion behaviour of the modified surfaces was compared with that of Ti in order to demonstrate that its initial good corrosion resistance is not strongly influenced due to surface alloying.     

Phase constituents and mechanical properties of laser in-situ synthesized TiCN/TiN composite coating on Ti-6Al-4V

Laser in-situ synthesis technology at room temperature was applied to obtain TiCN/TiN composite coating. A pulsed Nd:YAG laser (wavelength 1064 nm) was used to melt the mixture of Ti and C powder. Pure nitrogen gas with a pressure of 0.4 MPa was introduced coaxially together with laser beam to the melting pool to react with Ti and C atoms and in-situ synthesize TiCN/TiN composite coating. The coating consists of TiC_0.3N_0.7, TiN and TiN_0.3, but the proportions of these three constituents vary with the laser power density. SEM results revealed that dendrites were oriented in accordance with the heat flow and a metallurgical bonding between the coating and the substrate was achieved. The in-situ synthesized TiCN/TiN composite coating, with a thickness of about 200 μm, increased the hardness and wear resistance compared to the bare Ti-6Al-4V substrate. A remarkable improvement of the average microhardness (3-4 times) and an enhancement of the wear resistance (10-11 times) are observed by laser in-situ synthesizing TiCN/TiN composite coating.     

Structure and wear resistance of TiN and TiAlN coatings on AZ91 alloy deposited by multi-arc ion plating

In order to investigate the microstructure of TiN and TiAlN coatings and their effect on the wear resistance of Mg alloy, TiN and TiAlN coatings were deposited on AZ91 magnesium alloy by multi-arc ion plating technology. TiN and Ti70Al30N coatings were prepared on the substrate, respectively, which exhibited dark golden color and compact microstructure. The microstructures of TiN and Ti70Al30N coatings were investigated by X-ray diffractometry (XRD) and scanning electron microscopy (SEM). The micro-hardness and wear resistance of TiN and Ti70Al30N coatings were investigated in comparison with the uncoated AZ91 alloy. The XRD peaks assigned to TiN and TiAlN phases are found. The hardness of TiN coatings is two times as high as that of AZ91 alloy, and Ti70Al30N coating exhibits the highest hardness. The wear resistance of the hard coatings increases obviously as result of their high hardness.     

Microstructure and Tribological Properties of TiB2/TiB/TiNx（x=1,0.3）/Ti Composite Coating Produced on Pure Ti by Laser Surface Alloying

TiB2/TiB/TiNx(x=1,0.3)/Ti composite coating was prepared on pure Ti by laser surface alloying by using powders of boron as starting materials.The composite coating was examined by X-ray diffraction(XRD),high-resolution transmission electron microscopy(HRTEM)and scanning electron microscopy(SEM).The friction and wear properties of the composite coating were examined using a pin-on-disk tester under dry sliding wear condition.The results showed that the top surface of the composite coating was mainly composed of TiB2,TiB,TiN0.3,TiN and Ti phases,while the interface of the composite coating was composed of TiB and Ti phases.The composite coating showed sticklike structure near the top surface,and dendrites structure near the interface.The friction and wear test showed that the composite coating had better wear resistance than pure Ti due to their higher microhardness than that of pure Ti substrate.     

TC4表面反应电火花强化层物相及磨损行为分析

利用DZ-1400型电火花沉积／堆焊机,以工业纯钛TA2为电极,以工业纯氮为保护气和反应气,在TCA钛合金试件表面上制备了TiN／Ti复合涂层。利用X射线衍射仪分析了放电电容、输出电压、脉冲频率对涂层物相的影响,利用MH-6型显微硬度计测定涂层断面不同区域的显微硬度,利用KYKY2800扫描电镜观察涂层组织结构和磨损形貌,采用MS-T3000型球盘式摩擦磨损试验仪测试涂层的摩擦系数和磨损失重。结果表明,涂层中物相种类随放电电容、输出电压、脉冲频率的不同而变化。涂层组织致密,与基体之间形成冶金结合,涂层显微硬度呈梯度变化,涂层摩擦系数小,耐磨性好。     

陶瓷硬质相对铁基复合材料组织和性能的影响

采用明弧堆焊技术在Q235基体金属表面制备Fe-Cr-C-B-N-Ti系铁基复合材料. 借助金相显微镜、扫描电子显微镜、X射线衍射仪、洛氏硬度计和磨料磨损试验机对铁基复合材料的组织和性能进行分析与测试. 结果表明,铁基复合材料的基体组织由马氏体（M）和少量残余奥氏体（A）组成,硬质相由TiB₂,TiN,TiC,M₂₃（C,B）₆,M₃（C,B）和M₂B组成. 随着钛添加量的增多,初生陶瓷硬质相颗粒（TiB₂,TiN和TiC）和共晶硬质相（M₂₃（C,B）₆,M₃（C,B）和M₂B）增多,基体组织减少并细化. 当钛添加量为4%时,铁基复合材料的耐磨性达到最佳,此时硬度为66 HRC,磨损量为0.042 9 g.     

激光熔覆ZrB2-SiC增强Cu基复合涂层的微观结构与摩擦学性能

为了提高铜表面的强度和耐磨性,以复合粉末(Zr、Si、Ni包B4C、Cu)为原料,采用激光辅助原位合成技术,在纯铜基体表面制备了ZrB₂-SiC/Cu复合涂层。通过XRD、SEM和TEM分析了复合涂层的表面形貌、微观结构、相组成和界面结合,并测试了不同增强相含量熔覆层的硬度和摩擦学性能。结果表明：通过设计的原位化学反应成功在铜基体内合成了微米级针状ZrB₂和纳米级颗粒状SiC。增强相均与基体形成了清洁、无杂相的界面。2种不同维度与尺寸的增强体,通过多种强化机制,显著改善了复合涂层的力学性能;通过调整激光工艺参数可实现增强体尺寸的控制,随着增强相含量的提高,复合涂层的平均硬度和耐磨损性逐渐增加。当增强相含量为30%(质量分数,下同)时,复合涂层的平均硬度(HV0.2)为3028 MPa,约为纯铜的5.6倍。30%增强相涂层的载流磨损率与10%增强相的涂层相比,降低了约80%。较高含量增强相的复合涂层表现出优异的摩擦学性能。     

Surface engineering techniques used for improving the mechanical and tribological properties of the Ti6A14V alloy

The microstructure, mechanical and tribological properties of composite intermetallic layers of the Ti-Al system were investigated. The layers on the two-phase (α + β) Ti6Al4V titanium alloy were obtained using the hybrid method, which consist of two stages. First, the titanium alloy was covered with aluminum layer by magnetron sputtering. In the second stage, coated specimens were treated under glow discharge conditions. The surface treatment makes it possible to obtain the diffusional composite layers which considerably improve the mechanical and wear resistance properties of the material. These properties cannot be achieved using simple methods of surface engineering. The chemical and phase composition of the composite intermetallic layers was investigated. It has been shown that the hybrid method significantly increases the hardness and wear resistance of the titanium alloy and can widen the range of application of the material. Because of the diffusional character of the intermetallic layers they possess good adhesion to the titanium substrate.     

激光熔覆Mo2Ni3Si／NiSi金属硅化物复合材料涂层组织与耐磨性

以39Mo-35Ni-26Si(w％)合金粉末为原料，采用激光熔覆技术，在1Cr18Ni9Ti不锈钢基材表面翩得以Mo2Ni3Si金属硅化物为初生相，以Mo2Ni3Si／NiSi共晶相为基体的金属硅化物耐磨复合材料涂层。涂层的常温干滑动磨损试验结果表明，在磨损过程中，Mo2Ni3Si／NiSi共晶相轻微地优先磨损，Mo2Ni3Si金属硅化物微微凸出于磨损表面，起到抗磨的骨干作用。由于Mo2Ni3Si金属硅化物具有很高的硬度和很强的原子间键合力，在磨损过程中难于变形和粘着，激光熔覆Mo2Ni3Si／NiSi金属硅化物复合材料涂层具有优异的耐磨性，与1Cr18Ni9Ti标样相比，涂层的耐磨性提高了56倍。