Characterization of plasma-sprayed hydroxyapatite/TiO2 composite coatings

To enhance the bonding between hydroxyapatite (HA) coating and titanium alloy substrate, HA/TiO₂ composite coatings have been fabricatedvia plasma spraying. Bonding strength evaluation, simulated body fluid tests, and cell culturein vitro were carried out to characterize the composite coatings. The results obtained showed that the addition of TiO₂ to HA coating improved the bonding strength of the coating significantly. After being immersed in simulated body fluid (SBF) for a period, the surfaces of HA/TiO₂ composite coatings were completely covered by carbonate-containing apatite, which indicated that the coatings possess good bioactivity. Thein vitro cell culture indicated good cytocompatibility for HA/TiO₂ composite coatings.     

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....     

等离子喷涂人工骨涂层材料

等离子喷涂是一种常用的生物医用材料表面改性技术,被广泛应用于钛等金属人工骨的表面改性.为了满足人工骨涂层的临床应用需要,近年来发展了一些新的涂层材料和后处理工艺技术.利用火焰蒸汽处理技术对等离子喷涂羟基磷灰石涂层进行后处理,提高了涂层的结晶度,降低其在体液中的降解.经碱处理的等离子喷涂钛涂层,生物活性有了明显的改善.等离子喷涂硅灰石和硅酸二钙陶瓷是一类不同于传统磷酸钙系的新型生物活性材料,其性能和结构已被初步研究.同时介绍了等离子喷涂人工骨涂层材料在这几个方面的近期研究进展.     

Microstructure and properties of plasma-sprayed bio-coatings on a low-modulus titanium alloy from milled HA/Ti powders

New composite hydroxyapatite/titanium (HA/Ti) coatings were fabricated by plasma spraying on Ti–24Nb–4Zr–7.9Sn alloy from milled precursor powders. The microstructures, mechanical properties and apatite-induction abilities of the coatings were investigated, and the influences of the initial HA/Ti ratios on microstructure and properties were highlighted. XRD, SEM and TEM were used to analyze the microstructures of the coatings. The micro-hardness and elastic modulus were determined by indentation tests and the bond strength was determined by tensile tests. The apatite-induction ability of the coatings was evaluated in simulated body fluid (SBF) with ion concentrations similar to those of human blood plasma. The results showed that the microstructure, mechanical properties and apatite-induction ability were dependent on the HA/Ti ratios of the original powders. The mechanical properties increased, and the apatite-induction ability decreased with increasing Ti content. Various chemical reactions occurred during the preparation of the coatings, including the decomposition of HA, the reaction between HA and Ti and the oxidization of Ti, which resulted in the formation of new phases, such as CaTiO₃, Ca₃(PO₄)₂, TiP_x and titanium oxides in the different coatings. These new phases play an important role for the mechanical properties and the apatite-induction ability of the coatings.     

钛基材上电化学沉积羟基磷灰石

通过电沉积法在经过阳极氧化的钛基材表面沉积磷酸钙盐涂层,再经碱热处理使磷酸钙涂层转变为羟基磷灰石涂层。扫描电镜(SEM)观察了阳极氧化后生成的TiO2纳米管的微观结构,以及生成的羟基磷灰石的形貌。X射线衍射仪(XRD)分析了涂层的相组成,同时测定了涂层与基体的结合强度。试验结果表明:电沉积涂层CaHPO4·2H2O经碱处理后转变为羟基磷灰石;电沉积添加双氧水与钛基材经过阳极氧化后使得涂层与基体结合强度有所提高。模拟体液浸泡试验表明涂层具有良好的生物活性。     

Functionally graded carbon nanotubes/hydroxyapatite composite coating by laser cladding

Functionally graded carbon nanotubes/hydroxyapatite (CNTs/HA) composite coatings have been fabricated by laser cladding technique using CNTs/HA composite powders. As the feedstock for laser deposition, CNTs/HA composite powders were prepared by ball-milling different weight ratios (1%, 3% and 5%) of CNTs with HA powders. CNTs/HA composite coatings were fabricated with CNTs/HA composite powders and functionally graded coating was fabricated by sequentially depositing different CNTs/HA composite coatings on pure titanium. The phase composition, microstructure, micro-hardness, bonding strength and in vitro cellular responses of the composite coatings and the functionally graded composite coating were studied. The results show that the crystallinity of CNTs/HA composite coatings increased with increasing amount of CNTs in the powder mixture. The CNTs were dispersed homogeneously in the coatings to form an interconnected web and the cylinder graphic structure of CNTs was not changed after laser irradiation. Compared with pure HA coating, the maximum increase of the micro-hardness of CNTs/HA composite coatings was 46.8% and the micro-hardness of the functionally graded coating increased gradually through the thickness of this coating. Furthermore, the bonding strength of the functionally graded coating was nearly twice higher than that of pure HA coating. The in vitro cellular biocompatibility tests reveal that the functionally graded composite coating has comparable in vitro bioactivity with pure HA coating.     

Effects of TaN nanoparticles on microstructure,mechanical properties and tribological performance of PEEK coating prepared by electrophoretic deposition

In order to solve the friction, wear and lubrication problems of titanium, a series of TaN/ployether- ether-ketone (PEEK) coatings were developed by electrophoretic deposition, and the effects of TaN nanoparticles on the microstructure, mechanical properties and tribological performance of coatings were explored. Results manifest that the introduction of TaN nanoparticles into PEEK coatings could improve the deposition efficiency, enhance the resistant deform capacity, increase the hardness, elastic modulus and adhesive bonding strength. Compared with the pure PEEK coating, the friction coefficient of P-TN-3 was greatly reduced by 31.25%. The wear resistance of P-TN-3 was also improved in huge boost, and its specific wear rate was decreased from 9.42×10^-5 to 1.62×10^-5 mm³·N^-1·m^-1. The homogeneous composite TaN/PEEK coatings prepared by electrophoretic deposition were well-adhered to the titanium alloy substrate, TaN nanoparticles could improve the strength of PEEK coating, and provide wear-resistance protection for titanium alloys.     

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.     

CARBON FIBRE ELECTROPLATED BY Cu-Ni DUPLEX COATING AND ITS COMPOSITE

The carbon fibre was electroplated continuously by a duplex coating of Ni prior to Cu,andthe composite made of this carbon fibre together with Cu matrix has been investigated,thecompatibility between carbon fibre and duplex coating and flexural strength,linear thermalexpansion coefficient and electric resistivity of the composite have also been examined.Owingto the transformation of face-centred cubic Cu-Ni solid solution in the duplex coating underhigh temperatures,both the nodulizing shrinkage of Cu coating alone and the graphitizationof carbon fibre accelerated by single Ni coating with a consequent loss of strength were im-proved.Because of the dissolving of minute carbon fibre in the interfacial Cu-Ni solid solu-tion,the bonding strength and flexural strength of the composite were significantly increased,and the length of carbon fibre pulled out on the fracture surface was obviously reduced.Theinterface of the composite seems to be of the dissolution bonding.     

激光熔覆NiCrBSi/Ag复合涂层 结构及空间摩擦学性能

目的 提高钛及钛合金的空间摩擦学性能,拓展钛及钛合金在空间技术领域的应用范围。方法 用激光熔覆技术在纯钛基材表面制备了NiCrBSi/Ag复合涂层。用X-射线衍射仪、扫描电镜和高分辨透射电镜分析涂层的物相组成、显微组织结构和晶体结构。用空间摩擦学实验系统对NiCrBSi/Ag复合涂层在真空、原子氧和紫外辐照三种模拟空间环境以及大气环境下的摩擦学性能进行系统的研究。采用扫描电镜和能量色散光谱仪对摩擦测试后NiCrBSi/Ag复合涂层的磨痕形貌和对偶不锈钢钢球的磨痕形貌及元素面分布进行分析。深入探讨NiCrBSi/Ag复合涂层在三种模拟空间环境及大气环境下的磨损机理。结果 在纯钛基材表面通过激光熔覆制备的NiCrBSi/Ag复合涂层主要物相组成为NiTi、Ni3Ti、Cr2Ni3、Cr3Si、TiB2、Cr-Ni-Ti-Fe、Ag相,显微结构主要为等轴晶和枝状晶组织。复合涂层具有较高的显微硬度,涂层截面平均显微硬度约为830HV0.2,约是钛基材硬度的4.4倍。复合涂层在真空、原子氧和紫外辐照模拟空间环境下的摩擦系数和磨损率均小于大气环境下的值。在三种模拟空间环境下,相对于纯钛基材,复合涂层的磨损率约小2个数量级。复合涂层在真空、原子氧和紫外辐照模拟空间环境下的磨损机理为粘着磨损和磨粒磨损,在大气环境下的磨损机理主要为磨粒磨损。结论 NiCrBSi/Ag复合涂层可以显著提高纯钛基材在真空、原子氧和紫外辐照三种模拟空间环境以及大气环境下的摩擦学性能。     

Q345R板材表面冷喷涂Al-Zn涂层的组织及性能研究

目的 研究添加元素Zn含量的变化对涂层的显微组织、孔隙率、硬度及涂层-基体间界面结合强度等的影响规律.方法 采用冷喷涂技术在Q345R板材表面制备性能优良的纯Al和Al-Zn复合涂层,通过扫描电子显微镜对涂层的形貌进行分析,通过维氏显微硬度计对涂层的力学性能进行表征,并揭示涂层与基体间的界面结合机理.结果 冷喷涂纯Al...     

The evaluation of powder processing on microstructure and mechanical properties of hydroxyapatite (HA)/yttria stabilized zirconia (YSZ) composite coatings

In clinical applications, the mechanical failure of HA-coated titanium alloy implants suffered at the interface of the HA coating and titanium alloy substrate will be a potential weakness in prosthesis. Yttria stabilized zirconia (YSZ) reinforced HA coatings have been proven to enhance the mechanical properties of the HA coating significantly and reduce the formation of calcium oxide (CaO). In this paper, HA/YSZ (30 wt.% YSZ) composite coatings were sprayed by the plasma technique. The effects of the powder processing–mechanical ball milling method and spheroidization method on the microstructure and mechanical properties of the HA/YSZ composite coatings were evaluated. The experimental results showed that the spheroidized powders melted better than the ball milled powders during plasma spraying and formed higher mechanical property coatings (1.6326±0.08 MPa m^−0.5 of fracture toughness, 58.59±2.91 GPa of elastic modulus and 43.42±2.53 MPa of tensile bond strength). HA/YSZ solid solution formed during deposition on the substrate, which played a very important role in the mechanical properties of the HA/YSZ composite coatings. Tensile bond strength tests showed that the fracture mode was cohesive and that failure occurred at the interface of HA and unmelted YSZ particles. The molten state of YSZ had a great influence on the properties of the HA/YSZ composite coatings.     

Influence of FeCrAl Content on Microstructure and Bonding Strength of Plasma-Sprayed FeCrAl/Al<Subscript>2</Subscript>O<Subscript>3</Subscript> Coatings

Low-power plasma-sprayed FeCrAl/Al₂O₃ composite coatings with 1.5 mm thickness have been fabricated for radar absorption applications. The effects of FeCrAl content on the coating properties were studied. The FeCrAl presents in the form of a few thin lamellae and numerous particles, demonstrating relatively even distribution in all the coatings. Results show that the micro-hardness and porosity decrease with the increase in FeCrAl content. With FeCrAl content increasing from 28 to 47 wt.%, the bonding strength of the coatings with 1.5 mm thickness increases from 10.5 to 27 MPa, and the failure modes are composed of cohesive and adhesive failure, which are ascribed to the coating microstructure and the residual stress, respectively.     

TC4钛合金微弧氧化膜层高温氧化性能研究

利用微弧氧化(MAO)技术在TC4钛合金表面原位制备陶瓷膜层,并通过硅酸钠水溶液对膜层进行了封孔处理。采用X射线衍射仪(XRD)分析了膜层相组成,通过扫描电子显微镜(SEM)观察了膜层表面形貌。通过粘结拉伸测试,比较了膜层在封孔前后与基体的结合强度。利用高温氧化实验,考察了TC4基体及膜层试样封孔前后的抗高温氧化性能。结果表明:微弧氧化膜层与基体间的结合强度较高,经封孔处理及高温氧化100 h后,膜基结合强度降低至4.29 MPa。与TC4基体相比,微弧氧化膜层的高温氧化增重量小,抗高温氧化性能得到了显著的提高。封孔处理提高了微弧氧化膜层的致密性,使其能更好地阻止氧透过膜层向基体内侵入,进一步提高了膜层的抗高温氧化性能。     

Ca-P涂层在镁合金表面的形成特征

用化学方法在AZ91镁合金表面沉积二水磷酸氢钙涂层以提高镁合金在模拟体液中的生物降解能力。运用扫描电镜、X射线衍射对该涂层在模拟体液中浸泡前、后的显微组织进行分析。结果表明,在预钙化过程中形成的二水磷酸氢钙涂层呈现出两种不同的形貌。预钙化过程中钙化溶液的滴定速度强烈地影响预钙化涂层的形貌。随着钙化涂层在模拟体液中浸泡时间的延长,二水磷酸氢钙的衍射峰逐渐消失,羟基磷灰石在基底表面析出,表明二水磷酸氢钙在浸泡过程中发生溶解。详细讨论了二水磷酸氢钙涂层的结构以及羟基磷灰石涂层的形成机制。     

Study on Reactive Atmospheric Plasma-Sprayed In situ Titanium Compound Composite Coating

A titanium composite coating containing in situ synthesized oxides or nitrides was deposited on mild steel by reactive atmospheric plasma spraying. The relationships between the porosity, hardness, the phase composition of the sprayed coatings, and the spraying parameters were investigated. Titanium powders were used as starting powder materials. XRD analysis and microhardness test revealed that titanium oxides and nitrides were synthesized during the spraying process. The longer the spraying distance, the more the Ti nitrides’ content in the coating. It is shown that the Ti nitrides’ content has a significant influence on coating hardness. An in situ titanium composite coating with a hardness value of 1534HV_0.1 and an adhesive strength of 55.4 MPa was made with appropriate spraying parameters.     

等离子体增强磁控溅射CrSiN涂层摩擦磨损行为

目的基于细晶强化理论,借助新型涂层制备技术获得综合性能优良的CrSiN涂层,研究Si含量对涂层微观结构、力学性能及耐磨性能的影响规律。方法采用等离子体增强磁控溅射技术,制备四种含有不同Si含量的Cr Si N涂层。使用X射线能谱仪(EDS)、X射线衍射仪(XRD)、场发射扫描电子显微镜(FE-SEM)和原子力显微镜(AFM),分析涂层的化学成分、晶体结构、微观形貌和表面粗糙度。使用纳米压痕/划痕仪测试涂层的显微硬度、杨氏模量和结合力。使用摩擦磨损试验仪考察涂层的摩擦磨损行为。结果 Cr Si N涂层中Si含量随着Si靶功率的增加而增加。所有涂层中均未检测到含Si物相,主要由Cr N相组成。随着Si含量的增加,CrN(111)衍射峰逐渐减弱直至消失,涂层由疏松的三角锥结构逐渐变为致密平整的CrN纳米晶和Si3N4非晶共存的复合结构,涂层表面粗糙度显著降低,涂层的显微硬度、杨氏模量、结合力及耐磨性能均呈现先增后降的趋势。结论 Si含量为18.5%的Cr Si N涂层具有最佳的耐磨性能,此时涂层的硬度、杨氏模量、结合力和平均摩擦系数分别约为27 GPa、327 GPa、30 N和0.289。     

悬浮液等离子喷涂制备FHA/CS复合涂层

目的 采用悬浮液等离子喷涂技术（SPS）在纯钛表面制备氟代羟基磷灰石/硅酸钙（FHA/CS）生物复合涂层。方法 利用X射线衍射仪（XRD）、傅里叶红外光谱仪（FT-IR）、扫描电子显微镜（SEM）及能谱仪（EDS）对复合涂层的物相组成、组织结构和显微形貌进行分析。通过动电位极化测试和体外生物活性测试,分析复合涂层在模拟体液（SBF）中的腐蚀行为和类骨磷灰石形成能力。通过电感耦合等离子体光谱仪（ICP）分析涂层中Ca2+的释放行为,评估复合涂层的化学稳定性。采用划痕法表征涂层的结合强度。结果 SPS制备的复合涂层具有粗糙的表面和层片堆叠结构。涂层中FHA和CS两相分布均匀,结晶性良好。复合涂层临界载荷达到111.43 N,比单一FHA涂层提高62.5%。与纯钛相比,涂层样品具有较高的腐蚀电位（Ecorr）和较低的腐蚀电流密度（Jcorr）。在SBF溶液中浸泡3天,涂层样品表面被类骨磷灰石完全覆盖。ICP结果表明,复合涂层中Ca2+释放速率低于单一CS涂层。结论 通过SPS在纯钛表面制备的FHA/CS复合涂层具有良好的生物活性、耐腐蚀性能和与基体的结合强度,复合涂层中FHA组分的存在有利于提高涂层的化学稳定性。     

钛合金表面GO/HA/MAO复合膜层的制备及其性能

为了改善钛合金种植体在体液中的腐蚀及摩擦腐蚀行为,延长其在人体环境中的服役时间,在微弧氧化 (MAO)膜层上采用溶胶凝胶(Sol-gel)法于羟基磷灰石(HA)和氧化石墨烯(GO)的混合溶胶中浸渍提拉成膜,从而在 Ti6Al4V 合金表面成功地制备了 GO/ HA/ MAO 复合膜层。 结果表明,MAO 膜层表面的微孔及微球被 GO/ HA 薄膜有效的覆盖且较为致密;膜层的物相组成主要为金红石相及锐钛矿相的 TiO₂、HA、SiO₂ 和GO;根据电化学腐蚀和摩擦腐蚀结果分析知,GO/ HA/ MAO 复合膜层在模拟体液(SBF)中的耐蚀性及耐摩擦腐蚀性相比于 MAO 膜层和 Ti6Al4V 基体均得到了显著提高。     

基于晶体微观有限元方法的多相复合涂层高温摩擦应力场模拟

对高温摩擦磨损工况下多相复合涂层的热-力耦合应力场的模拟研究尚不充分。基于Voronoi多边形建立NiCr-Cr₃C₂-CaF₂/BaF₂多相复合涂层的晶体微观有限元模型,模拟复合涂层中各相的占比、分布形态和热-力学参数,求解得到热-力耦合工况下的von Mises应力和第一主应力分布。结果表明：在高温摩擦工况下,多相复合涂层的应力显著高于均匀涂层,尤其是在硬质相尖端附近易产生局部高应力区域,改善相的形态将锐角钝化能够有效缓解局部高应力现象;热-力耦合应力场与黏结相和硬质相的弹性模量密切相关,通过调节各相模量能够有效调控复合涂层的Mises应力和拉应力值。基于微观有限元方法的热-力耦合应力场模拟可为高温摩擦磨损工况下多相复合涂层的优化设计提供理论依据。