复合表面改性协同增强Ti合金高温微动疲劳抗力

研究了Ti811（Ti8A11MolV）钛合金表面离子束增强沉积（IBED）0Cr18Ni9膜层的膜基界面成分分布、膜基结合强度、膜层硬度和摩擦学行为。利用喷丸形变强化对IBED膜层进行后处理，拟达到联合提高钛合金高温微动疲劳抗力的目的。结果表明：离子束增强沉积技术可以获得致密度高，晶粒细化，孔隙率低，膜基结合强度高的0Cr18Ni9膜层，从而显著提高了钛合金表面硬度和耐磨性能；离子束增强沉积0Cr18Ni9膜层的耐磨性能与喷丸形变强化引入的表层残余压应力协同作用，使Ti811合金在350℃高温下的微动疲劳抗力显著提高，并且高于喷丸强化或IBED膜层的单独作用。     

Cu/Ni多层膜对Ti811合金微动磨损和微动疲劳抗力的影响

在Ti811钛合金表面利用离子辅助磁控溅射沉积技术制备20～1200nm不同调制周期的Cu/Ni金属多层膜,分析多层膜的结构,测试膜基结合强度、膜层显微硬度和韧性,对比研究不同调制周期的Cu/Ni多层膜对钛合金基材常温下微动磨损性能和微动疲劳(FF)抗力的影响。结果表明:利用离子辅助磁控溅射技术可以获得致密度高、晶粒细化、膜基结合强度高的Cu/Ni多层膜,该类多层膜具有良好的减摩润滑作用,因而改善了Ti811钛合金常温下抗微动磨损和微动疲劳性能;Cu/Ni多层膜对钛合金FF抗力的改善程度随膜层调制周期呈现非单调变化趋势,调制周期为200nm的Cu/Ni多层膜对钛合金FF抗力的提高程度最大,原因归于该膜层具有良好的强韧和润滑综合性能。     

钛合金表面离子束增强沉积MoS2基膜层及其性能

将离子束增强沉积（IBED）技术与离子束溅射的沉积技术相结合,在钛合金表面制备了MoS2,MoS2-Ti复合膜。研究了膜层的形态、结构、膜基结合强度、硬度、摩擦学性能及抗微动（fretting）损伤性能。结果表明;所获膜层较纯溅射膜结合强度高、致密性好,复合膜中允许的金属元素含量大。通过恰当地控制复合膜中Ti的含量,可获得以（002）基面择优取向的MoS2-Ti复合膜,该膜层有较好的减摩和抗磨综合性能,能够显著地改善钛合金的常规磨损、微动摩员（FW)和微动疲劳（FF）性能,特别是在磨损严重的大位移整体滑条件下,MoS2-Ti复合膜对钛合金FF抗力的提高作用可大于喷丸形变强化处理。     

TC4钛合金表面渗碳复合TiN(Ti)膜层的抗冲蚀性能研究

硬质膜层能够显著提高飞机发动机钛合金叶片的抗固体颗粒冲蚀性能,现有的软基体/硬膜层体系由于较高的脆性及界面不匹配性很容易被冲蚀,膜基界面极易发生脆性剥落。为了改善硬质膜层的抗冲蚀性能,结合辉光离子扩渗及等离子增强电弧离子镀技术,本文在TC4合金表面制备了具有梯度渗碳及TiN(Ti)膜层的复合渗镀层,并表征了结构对于复合渗镀层性能的影响。结果表明,相对于未强化的TC4基体表面单层TiN及12周期复合Ti/TiN膜层,复合渗镀层的显微硬度及膜基结合强度均同步得到了提高。冲蚀试验结果表明,TC4基体未渗碳前,表面单层TiN膜层呈现出脆性冲蚀开裂机制,12层复合Ti/TiN膜层由于多层复合结构的增韧效应,呈现出层状剥落及“冲蚀窝”损伤形貌。渗碳后,复合渗镀层的抗冲击韧性得到提高,单层TiN膜层在冲蚀条件下的膜基界面脆性开裂明显被抑制。渗碳复合12周期复合Ti/TiN结构的复合渗镀层具有最佳的抗固体颗粒冲蚀性能,表现出明显的韧性损伤机制,冲蚀失重率降低了十余倍。抗冲蚀性能的提高可归结于复合渗镀层较高的表面硬度、界面强度和强韧性匹配。     

真空退火对TC4钛合金表面Ti/TiN多层复合涂层性能的影响

金属基体材料表面硬质膜层在服役过程中,残余应力在膜基界面以及膜层内部界面之间的积聚会导致膜层发生界面剥落失效。以TC4钛合金基体表面Ti/TiN多层复合膜层为研究对象,探讨真空退火对复合膜层结构及性能的影响,并表征退火前后复合膜层的界面划痕失效以及抗粒子冲蚀性能。结果表明,真空退火促进了膜层内部以及膜基界面两侧原子的热扩散,使得界面结构特征明显弱化。界面状态的改变使得复合膜层的表面显微硬度降低以及膜基结合强度提高。在划痕载荷作用下,复合膜层抵抗裂纹沿界面扩展的能力得到增强。真空退火有助于提高膜层的强韧性匹配,可有效抵抗小角度冲蚀粒子的犁削以及大角度粒子冲蚀下的疲劳,因此Ti/TiN多层复合膜层表现出较好的抗冲蚀性能。     

等离子渗氮与喷丸强化复合改进钛合金抗微动损伤性能

利用直流脉冲等离子电源装置对Ti6A14V钛合金表面渗氮处理,研究了渗氮层的相组成、硬度分布、韧度及摩擦学性能,采用喷丸形变强化(SP)对渗氮层进行后处理,以达到联合提高钛合金微动疲劳(FF)抗力的目的.研究结果表明:脉冲电源等离子技术可在钛合金表面获得由TiN、Ti2N、Ti2A1N等相组成的渗氮层,该改性层能够显著地提高钛合金常规磨损和微动磨损(FW)抗力,但降低了基材的FF抗力.渗氮层的减摩和抗磨性能与SP引入的表面残余压应力协同作用,使钛合金FF抗力超过了SP单独作用.提高渗氮层韧度对改善钛合金FF和FW性能均十分重要.     

Mo电极电火花强化与喷丸复合提高Ti合金微动疲劳抗力

采用Mo电极分别在空气和硅油中对Ti811钛合金表面进行电火花强化处理（ESS），探讨消除强化层中裂纹缺陷的途径。将ESS与喷丸强化复合，拟使Ti合金微动疲劳（FF）抗力得到显著改善。结果表明：Mo电极在空气中电火花强化处理Ti811钛合金表面后，强化层出现明显的微裂纹缺陷，由此导致其微动疲劳抗力降低。在硅油中用Mo电极电火花处理Ti811合金不仅消除了表面裂纹缺陷，而且使钛合金表面具有良好的减摩润滑作用，显著改善了钛合金基材的耐磨性能；再经喷丸强化处理，使钛合金基材的微动疲劳抗力显著提高。     

离子渗ZrN与喷丸复合对TC4合金疲劳行为的影响

为改善钛合金耐磨和抗疲劳性能,采用离子渗技术在TC4钛合金表面先渗Zr,再渗N形成梯度ZrN合金化层,并与喷丸强化(SP)后处理复合。采用扫描电镜(SEM)、X射线衍射仪和显微硬度计分析测试了改性层的组织结构和硬度沿层深的分布,探讨了改性层对TC4钛合金疲劳性能的影响规律和作用机制。结果表明,TC4钛合金离子渗层由ZrN-TiN复合相表层和富氮的Zr-Ti固溶体次表层组成,表面以ZrN相为主,其硬度较基材提高了3.2倍,合理强度的喷丸后处理未造成渗ZrN层表面明显损伤,并使表层硬度进一步增大,硬度沿层深呈现梯度递减分布。渗ZrN层明显降低了TC4合金的疲劳抗力,此归于ZrN-TiN层韧性低、表面粗糙度大。SP后处理则使渗ZrN的TC4钛合金疲劳抗力显著提高,不仅远高于TC4钛合金基材,而且远大于SP处理状态,原因归于复合处理引入了数值高、分布深的残余压应力场,并使表面粗糙度降低、组织改善,有效抑制了疲劳裂纹的萌生和扩展。     

Ti/TiN/Zr/ZrN多层膜对1Cr17Ni2不锈钢疲劳性能的影响

采用真空阴极电弧沉积技术在1Cr17Ni2马氏体型不锈钢表面沉积Ti/TiN/Zr/ZrN多层膜。研究对比了在室温下膜层试样与基体试样的旋转弯曲疲劳强度、疲劳寿命和疲劳断裂机理。结果表明:在不锈钢基体上沉积厚度为11.7μm,硬度为3 220HV0.025,膜/基结合力为56N的Ti/TiN/Zr/ZrN多层膜后,其疲劳性能显著提高,膜层试样较基体试样的疲劳极限提高了约11.2%,当应力水平在540～650 MPa变化时,疲劳寿命增量变化范围为108%～246%;裂纹均起源于表面,在低应力水平下只有一个裂纹源,而高应力水平下有多个裂纹源;疲劳性能的提高主要是由于膜层能够弥补基体表面一定的缺陷,同时软硬交替的膜层结构有较强的抗裂纹扩展能力。     

喷丸预处理对Ti6Al4V合金低温等离子体氮化的影响

为改善钛合金表面耐磨性能,同时达到防止薄壁零部件变形和节约能源的目的,以Ti6Al4V钛合金为对象,研究了喷丸强化预处理对钛合金低温渗氮层及耐磨性的改善作用。结果表明,喷丸强化预处理能够有效促进钛合金表面低温离子渗氮过程,在500 ℃低温渗氮试验条件下,随着喷丸预处理强度的增大,钛合金渗氮效率逐步提高,渗氮层的表面硬度、承载能力和表观韧性逐步增加,使得渗氮层的耐磨性能逐步提高。当喷丸预处理强度增加到0.25 mmA时,Ti6Al4V钛合金渗氮层的表面硬度比单纯渗氮处理试样提高32.7%,磨损率降低42.3%,使钛合金基体的磨损率降低70.5%,较好地实现了喷丸预处理促进钛合金低温离子渗氮的目标。     

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.     

Effect of TiN/Ti multilayer on fretting fatigue resistance of Ti-811 alloy at elevated temperature

The TiN/Ti multilayer was deposited on Ti-811 alloy surface by magnetron sputtering(MS) technique for improving fretting fatigue(FF) resistance of the titanium alloy at elevated temperature. The element distribution, bonding strength, micro-hardness and ductility of the TiN/Ti multilayer were measured. The effects of the TiN/Ti multilayer on the tribological property and fretting fatigue resistance of the titanium alloy substrate at elevated temperature were compared. The results indicate that by MS technique a TiN/Ti multilayer with high hardness, good ductility and high bearing load capability can be prepared. The MS TiN/Ti multilayer, for its good toughness and tribological behavior, can significantly improve the wear resistance and FF resistance of the Ti-811 alloy at 350 ℃.     

Influence of surface coating on Ti811 alloy resistance to fretting fatigue at elevated temperature

An extensive study of the composition distribution, bonding strength, hardness, and wear resistance of a 0Cr18Ni9 film deposited on a Ti811 titanium alloy surface by ion beam enhanced deposition (IBED) is presented. Shot peening was introduced to post-treat the modified surface to synergistically improve the fretting fatigue resistance of the Ti811 alloy at 350～C. The results indicate that the 0Cr18Ni9 film with high density, small grain size, low void radio, and high bonding strength can be prepared using IBED. As a result, the hardness, wear resistance, and fretting fatigue resistance of the Ti811 alloy are increased to a remarkable extent. Compared with shot peening treatment or IBED 0Cr18Ni9 film alone, the Ti811 titanium alloy with an IBED 0Cr18Ni9 film combined with shot peening shows a higher fretting fatigue resistance at 350℃. This is due to the synergistic effect of the high wear resistance of the film surface and the residual compressive stress induced by shot peening.     

Effects of temperature, slip amplitude, contact pressure on fretting fatigue behavior of Ti811 alloys at elevated temperatures

Effects of the temperature,slip amplitude,and contact pressure on fretting fatigue(FF) behavior of the Ti811 titanium alloy were investigated using a high frequency fatigue machine and a home-made high temperature apparatus.The fretting fatigue failure mechanism was studied by observing the fretting surface morphology features.The results show that the sensitivity to fretting fatigue is high at both 350 and 500 °C.The higher the temperature,the more sensitive to the fretting fatigue failure is.Creep is an i...     

Surface characterization and mechanical property of TiN/Ti-coated NiTi alloy by PIIID

A hard and adherent TiN/Ti thin film of approximately 3 μm in thickness was deposited on the surface of Ti-50.6 at.% Ni alloy by the PIIID technique. The surface composition and chemical state of the coated samples were evaluated by XPS. The XPS results indicate that titanium oxide and titanium oxynitride were present on the TiN surface. The spectra of Ti 2p, N 1s, O 1s and C 1s electrons before and after the film being sputter etched were also discussed. Scanning electron microscopy (SEM) and energy disperse spectroscopy (EDS) analyses demonstrate that an interfacial layer, containing Ti, N and Ni, was formed at the interface between the TiN and Ti coatings. Sliding wear tests show that the TiN coating significantly reduces the friction coefficient and improves wear resistance of the NiTi alloy.     

Fretting wear behavior of Ti/TiN multilayer film on uranium surface under various displacement amplitudes

Ti/TiN multilayer film was deposited on uranium surface by arc ion plating technique to improve fretting wear behavior. The morphology, structure and element distribution of the film were measured by scanning electric microscopy (SEM), X-ray diffractometry (XRD) and Auger electron spectroscopy (AES). Fretting wear tests of uranium and Ti/TiN multilayer film were carried out using pin-on-disc configuration. The fretting tests of uranium and Ti/TiN multilayer film were carried out under normal load of 20 N and various displacement amplitudes ranging from 5 to 100 μm. With the increase of the displacement amplitude, the fretting changed from partial slip regime (PSR) to slip regime (SR). The coefficient of friction (COF) increased with the increase of displacement amplitude. The results indicated that the displacement amplitude had a strong effect on fretting wear behavior of the film. The damage of the film was very slight when the displacement amplitude was below 20 μm. The observations indicated that the delamination was the main wear mechanism of Ti/TiN multilayer film in PSR. The main wear mechanism of Ti/TiN multilayer film in SR was delamination and abrasive wear.     

钛生物医学材料耐蚀性能研究进展

综述了钛生物医学材料在体液中的耐蚀性能.主要阐述了局部腐蚀、磨损腐蚀、腐蚀疲劳和应力腐蚀破裂等4种腐蚀形式.进而展望了目前钛生物材料的研究动向及应用前景.