微束等离子喷涂羟基磷灰石涂层

采用微束等离子喷涂(MPS) 在Ti6Al4V基体上制备了羟基磷灰石(HA)涂层, 并以大气等离子喷涂(APS)为对照. 利用光学显微镜、SEM和XRD分析技术对MPS涂层形貌、相组成和结晶度进行了研究. 结果表明: 在微束等离子喷涂过程中, HA 的分解程度比大气等离子喷涂有显著降低, 除了HA相, 仅形成β-TCP相和非晶相. MPS涂层的结晶度主要受喷涂距离的影响. 喷涂距离较短(<80mm)时, 涂层结晶度高于APS方法制备的涂层. 喷涂距离在130mm时, 涂层结晶度低. 大气等离子喷涂层含有β-TCP、α-TCP、TTCP、CaO和非晶. MPS涂层分解较APS少的主要原因是喷涂过程中HA粒子过热不严重.     

Ti-Al双丝超音速电弧喷涂涂层的滑动磨损特性研究

为了提高铝合金(LY12)的表面耐磨性,采用钛、铝金属丝材和SAS-Ⅰ型超音速电弧喷涂设备,利用二次回归正交试验方法、有润滑滑动磨损试验、涂层显微组织和磨损表面形貌观察、XRD分析,定量分析了喷涂电压和喷涂距离对涂层滑动磨损体积的影响规律,并进行了喷涂工艺参数的优化及其与基体滑动磨损的对比试验.结果表明:在特定的磨损和喷涂条件下,当喷涂距离较小时,随喷涂电压的增大,涂层的体积磨损量逐渐减小;随着喷涂距离的增加,涂层的体积磨损量随喷涂电压的升高逐渐增大,并且喷涂距离越大,涂层的体积磨损量随喷涂电压增大的速率愈大.当喷涂电压比较低时,涂层的体积磨损量随喷涂距离的增大而降低,但是,随喷涂电压的逐渐升高,涂层的体积磨损量随喷涂距离的增大逐渐上升,并且,喷涂电压愈高,其随喷涂距离而增加的速率越快.当喷涂电压和喷涂距离分别为26V和0 236m时,涂层具有最佳的耐滑动磨损性能,根据该工艺参数制成的涂层,其滑动磨损体积仅为LY12铝合金的1/38.84.即在适当的工艺条件下,Ti-Al双丝超音速电弧喷涂涂层对LY12铝合金具有显著的表面耐磨强化作用.     

Enhanced osteointegration of orthopaedic implant gradient coating composed of bioactive glass and nanohydroxyapatite

We conducted histologic and histomorphometric studies to evaluate the osteointegration of gradient coatings composed of bioactive glass and nanohydroxyapatite (BG–nHA) on titanium-alloy orthopaedic implants and surrounding bone tissue in vivo. Titanium-alloy implants with a gradient coating (gradient coating group), uncoated implants (uncoated group), and implants with a conventional hydroxyapatite (HA) coating (HA coating group) were randomly implanted in bilateral femoral condyles of 36 male New Zealand rabbits. The bone–implant contact at 12 and 24 weeks and the new bone volume in the notch created for observing bone ingrowth at 4, 12, and 24 weeks were found greater in the gradient coating group than those in both the uncoated group and the HA coating group (p < 0.05). Fluorescence micrographs showed active osteogenesis in the gradient coating group at 4 weeks after implantation. These findings indicated that BG–nHA gradient coatings could enhance the osteointegration of orthopaedic implant.     

等离子喷涂制备HA/ZrO2复合涂层

采用等离子喷涂技术,在Ｔｉ－６Ａｌ－４Ｖ基体上成功地制备了羟基磷灰石／氧化锆（ＨＡ／ＺｒＯ２）复合涂层,对涂层的微观结构,相组成和结合强度进行了研究,并以模拟体液试验评估涂层的生物活性,结果表明,复合涂层较有较为微观结构,ＨＡ／ＺｒＯ２复合涂层的结合强度明显高于ＨＡ涂层,ＨＡ／６０ｗｔ％ＺｒＯ２涂层的结合强度高达２８．５ＭＰａ,为ＨＡ涂层的２．２倍,复合涂层在模拟体液中浸泡一段时间后,表面覆盖一层     

Preparation of an electrodeposited hydroxyapatite coating on titanium substrate suitable for in-vivo applications

In this paper the porous hydroxyapatite coating on Ti implant materials was prepared by the process of electrodeposition, hydrothermal and sinter. The surface morphology, bond strength and thickness of HA coatings were investigated by SEM, AFM, and its biocompatibility was evaluated by cytotoxicity experiments and implant experiments, respectively. Results showed that (1) The HA coatings was 50 μm thickness and adhered on the Ti substrate strongly, which bond strength reached 38MPa. AFM analysis showed that the HA coating was porous structure, in which the mean pore size was 236.5 μm, (2) Cytotoxicity experiments and implant experiments showed that HA-coated Ti implant materials has little cytotoxicity in vitro and little inflammatory reaction in vivo, and there were no statistically disparity between HA-coated Ti implant and titanium implant materials of clinical application (p > 0.05), which demonstrated that HA-coated Ti has a good biocompatibility.     

等离子喷涂制备HA/ZrO2复合涂层

采用等离子喷涂技术,在Ｔｉ－６Ａｌ－４Ｖ基体上成功地制备了羟基磷灰石／氧化锆（ＨＡ／ＺｒＯ_２）复合涂层,对涂层的微观结构、相组成和结合强度进行了研究,并以模拟体液试验评估涂层的生物活性．结果表明,复合涂层具有较为均匀的微观结构．ＨＡ／ＺｒＯ_２复合涂层的结合强度明显高于 ＨＡ涂层, ＨＡ／６０ ｗｔ％ ＺｒＯ_２涂层的结合强度高达 ２８．５ＭＰａ,为 ＨＡ涂层的 ２．２倍．复合涂层在模拟体液中浸泡一段时间后,表面覆盖一层碳酸磷灰石（ｃａｒｂｏｎａｔｅ－ａｐａｔｉｔｅ）,表明涂层具有良好的生物活性．     

Biomimetic nanostructured coatings on nano-grained/ultrafine-grained substrate: Microstructure, surface adhesion strength, and biosolubility

We describe here the structural morphology, nucleation and growth, surface adhesion response and biosolubility in simulated physiological fluid of nanohydroxyapatite (nHA)-based coatings (nHA, chitosan-nHA, collagen-nHA) on nano-grained (NG)/ultrafine-grained (UFG) 316L austenitic stainless steel bulk substrate. The NG/UFG stainless steel was processed by a novel procedure involving controlled phase reversion of strain-induced martensite. Electron microscopy studies indicated that the morphology of nHA on NG/UFG stainless steel is characterized by a vein-type interconnected structure consisting of fibrils that closely mimics the fibrous structure present as part of the hierarchical structure of the bone. Interestingly, the dimensions of the vein-type interconnected structure were similar to the grain size of NG/UFG stainless steel substrate. This structural morphology was retained in crystallized chitosan-nHA coating, but was modified when collagen is codeposited with nHA. The mechanisms of deposition are discussed based on the structural characteristics of coatings. Adhesion response of coating as determined by scratching tests suggested superior adhesion strength of nHA coating on NG/UFG substrate as compared to that on CG substrate and is attributed to grain size effect and wettability of the substrate.     

Compositional and structural control in bone regenerative coatings

The development of a low-temperature method of producing bioactive coatings for medical implants has been shown to bypass the problems associated with high temperature processing routes, in particular the appearance of amorphous phases and non-stoichiometric hydroxyapatite (HA), and delamination of the coating from the substrate. An electric field/aqueous solution technique for producing adherent, crack-free calcium phosphate coatings on titanium and stainless steel substrates is described. The characteristics of the coating are a function of electrode spacing, supersaturation, temperature and current and voltage conditions. Scanning electron microscopy (SEM) characterized the surface morphology of the coatings, which were shown to be HA. The possibility of producing a coating of carbonate-substituted HA having the same chemical composition as bone apatite, and forming at physiological temperatures, has also been demonstrated. The size of the microstructure decreased and the morphology changed as the carbonate ion concentration in the calcium and phosphate ion solution increased. © 1999 Kluwer Academic Publishers     

等离子喷涂工艺参数对FeCrBSi合金涂层结合强度的影响

采用等离子喷涂工艺在Q235钢基体上直接制备了FeCrBSi合金涂层,使用正交试验法研究了喷涂工艺参数对涂层结合强度的影响,并对喷涂工艺参数进行了优化,同时在优化参数的基础上进一步研究了涂层厚度对结合强度的影响。结果表明：等离子喷涂制备FeCrBSi合金涂层的最佳工艺参数为喷涂电流900A,主气流量44．8L·min-1,辅气流量27．8L·min-1,喷涂距离110mm;采用最佳工艺制备的涂层与基体的结合强度为18．2MPa,内聚强度为33．5MPa;随着涂层厚度的增加,涂层与基体的结合强度明显下降,而涂层的内聚强度先上升后下降,较佳的涂层厚度为347．2μm。     

Nano-structural bioactive gradient coating fabricated by computer controlled plasma-spraying technology

The poor mechanical property of hydroxyapatite was the major problem for load bearing and implant coating in clinical applications. To overcome this weakness, a bioactive gradient coating with a special design composition of hydroxyapatite (HA), ZrO₂, Ti, bioglass was developed. This 120 μm coating with an upper layer of 30–50 μm porous HA produced by computer controlled plasma spraying which maintained energy level of the plasma which ensure proper melting of powder. The crystal size of the coating was 18.6–26.2 nm. Transformation of t-ZrO₂ to m-ZrO₂ reduced the thermal stress that weakened the coating and lowered down interfacial strength of the coating and metal substrate. Thermal stress of sprayed coating was 16.4 MPa which was much smaller than the sample without thermal treatment of 67.1 MPa. Interfacial strength between the coating and metal substrate was 53 MPa which is much higher than conventional Hydroxyapatite coating. Based on XRD analysis crystallinity of HA approached 98%. Therefore, high temperature treatment improved long term stability of the coating through improved crystallinity of hydroxyapatite and reduced other impure calcium phosphate phase.     

等离子喷涂HA/Ti复合涂层研究 I.结构、组成和力学性能

采用等离子喷涂方法,在Ｔｉ－６Ａｌ－４Ｖ基体上成功地制备了ＨＡ／Ｔｉ复合涂层,并对复合涂层的微观结构、相组成和力学性能进行了研究．结果表明,ＨＡ和Ｔｉ两相均匀地分布于复合涂层中．ＨＡ／Ｔｉ复合涂层的结合强度明显高于纯 ＨＡ涂层,这主要是由于 ＨＡ／Ｔｉ的复合缓和了涂层与基体之间的热膨胀系数失配．ＨＡ／Ｔｉ复合涂层在模拟体液中浸泡一段时间后,结合强度没有明显降低．ＨＡ／Ｔｉ复合涂层的断裂韧性和硬度均高于 ＨＡ涂层．     

Production and characterization of HA and SiHA coatings

Plasma sprayed hydroxyapatite (HA) coatings on metallic prostheses have been used clinically in dentistry and orthopedics since the mid 1980s. The coating properties are dependent on the spraying parameters. Since silicon-substituted hydroxyapatite (SiHA) has been shown to offer improved bioactivity over phase pure HA, SiHA coatings have the potential for enhanced performance in clinical application. In this study, phase pure HA and 0.8 wt% SiHA powders were synthesized with similar particle size distribution and morphology. The powders were plasma sprayed onto Ti–6Al–4V substrates at 37 kW and 40 kW plasma gun input power respectively. Four kinds of samples were prepared, HAC 37, HAC 40, SiHAC 37 and SiHAC 40. Materials characterization showed that the coatings were of relatively high phase purity. In vitro cell culture demonstrated that human osteoblast cells grew well on all samples, with the highest cell growth observed on SiHA coatings produced under the lower plasma gun input power.     

电弧喷涂工艺参数对1Cr13涂层与45钢结合强度的影响

电弧喷涂技术常用于机械零件如柱塞、曲轴等的修复.喷涂层与基体的结合强度直接影响其寿命,并与喷涂工艺有密切的关系.用正交设计试验方案,在45钢基体上采用电弧喷涂方法制备了1Cr13涂层,并通过涂层结合强度试验考察了喷涂工艺参数与涂层结合强度的关系.结果表明:电弧喷涂1Cr13钢丝的优化工艺参数为:电压32 V,电流240 A,喷涂压力0.7 MPa,喷涂距离150 mm;影响涂层结合强度的工艺参数从主到次依次为电弧电流、喷涂压力、喷涂距离和喷涂电压.     

Silicon-substituted hydroxyapatite composite coating by using vacuum-plasma spraying and its interaction with human serum albumin

The incorporation of silicon can improve the bioactivity of hydroxyapatite (HA). Silicon-substituted HA (Ca₁₀(PO₄)_6−x (SiO₄) _x (OH)_2−x , Si-HA) composite coatings on a bioactive titanium substrate were prepared by using a vacuum-plasma spraying method. The surface structure was characterized by using XRD, SEM, XRF, EDS and FTIR. The bond strength of the coating was investigated and XRD patterns showed that Ti/Si-HA coatings were similar to patterns seen for HA. The only different XRD pattern was a slight trend toward a smaller angle direction with an increase in the molar ratio of silicon. FTIR spectra showed that the most notable effect of silicon substitution was that –OH group decreased as the silicon content increased. XRD and EDS elemental analysis indicated that the content of silicon in the coating was consistent with the silicon-substituted hydroxyapatite used in spraying. A bioactive TiO₂ coating was formed on an etched surface of Ti, and the etching might improve the bond strength of the coatings. The interaction of the Ti/Si-HA coating with human serum albumin (HSA) was much greater than that of the Ti/HA coating. This might suggest that the incorporation of silicon in HA can lead to significant improvements in the bioactive performance of HA.     

Ti-HA-BaTiO_3生物复合材料的制备与性能

为进一步提高骨修复材料的骨诱导性能,引入了BaTiO_3压电涂层。首先,通过等离子喷涂法在Ti基体上制备羟基磷灰石(HA)、Ti-HA和Ti-HA-BaTiO_3这3种生物涂层;然后,采用正交试验设计优化了喷涂工艺参数,用SEM/EDS对涂层的形貌和成分进行了表征,并通过划痕试验测试了涂层与基体的结合强度;最后,进行了细胞培养试验,用CCK-8法对细胞毒性进行了评价,并在SEM下观察了细胞的粘附形态。结果显示:细胞带有伪足,呈梭形和不规则多边形,且粘附在Ti-HA-BaTiO_3复合涂层表面;细胞伸展形态良好,涂层的细胞毒性等级不高于1级。可见,Ti-HA-BaTiO_3复合材料可以作为临床植入材料应用。     

Structure and properties of hydroxyapatite-bioactive glass composites plasma sprayed on Ti6Al4V

Hydroxyapatite (HA)-coated Ti6Al4V has recently been used as a bone substitute in orthopaedic and dental applications because of its favourable bioactivity and mechanical properties. Studies in the literature have shown that the bioactivity of calcium phosphate bioactive glass (BG) is higher than that of HA. In an attempt to increase the bioactivity of Ha-coated Ti6Al4V and enhance the bonding strength between coating and substrate, in the present study, HA/BG composites are applied onto Ti6Al4V using a plasma spraying technique. Microstructure and phase changes of the composite coating after plasma spraying are studied. The coating-substrate bonding strength is evaluated using an Instron, following the ASTM C633 method. Results indicate that the average bonding strengths of BG, HA/BG and HA coatings are 33.0±4.3, 39.1±5.0, and 52.0±11.7 MPa, respectively. Open pores with sizes up to 50 m are found in both BG and HA/BG coatings, which are probably advantageous in including mechanical interlocking with the surrounding bone structure, once implanted. These HA/BG composites could provide a coating system with sufficient bonding strength, higher bioactivity, and a significant reduction in cost in raw materials. The future of this HA/BG composite coating system seems pretty bright.     

等离子喷涂WC-12Co涂层的组织与性能

为了提高WC-12Co涂层的喷涂质量,采用大气等离子喷涂(APS)方法在Q235钢基体上制备WC-12Co复合涂层,探讨了不同工艺参数下涂层的组织与性能,用扫描电镜(SEM)、X射线衍射仪(XRD)和能谱仪(EDS)研究涂层形貌和微观组织及涂层成分演变规律,采用显微硬度计测试涂层显微硬度。结果表明:涂层主要由WC和W2C以及少量的Co3W3C和Co6W6C相组成;涂层主要以机械结合方式为主,厚度大约在300μm,粘结层厚度约为60μm。该试验最优工艺参数为电流300 A,送粉率50 g/min,喷涂距离110 mm;优化后涂层硬度为1 169HV0.5 N,孔隙率为3.6%。     

等离子喷涂HA/Ti复合涂层研究 I.结构、组成和力学性能

采用等离子喷涂方法,在Ｔｉ－６Ａｌ－４Ｖ基体上成功地制备了ＨＡ／Ｔｉ复合涂层,并对复合涂层的微观结构,相组成和力学性能进行了研究。结果表明,ＨＡ和Ｔｉ两相均匀地分布于复合涂层中。ＨＡ／Ｔｉ复合涂层的结合强度明显高于纯ＨＡ涂层,这主要是由于ＨＡ／Ｔｉ的复合和了涂层与基体之间的热膨胀系数失配,ＨＡ／Ｔｉ复合涂层在模拟体液中浸泡一段时间后,结合强度没有明显降低,ＨＡ／Ｔｉ复合涂层的断裂韧性和硬度均高于Ｈ     

Bimodal TBCs with low thermal conductivity deposited by a powder-suspension co-spray process

Advanced thermal barrier coatings (TBCs) with better thermal barrier performance are required by both advanced gas turbine and air engine. In this work, novel bimodal TBCs with low thermal conductivity were deposited and characterized by a novel co-spray approach with both solid powder and suspension. Experimental and finite element analyses were used to optimize the process parameters to prepare the specific morphology nanostructure features. With a comprehensive understanding on the influence of spraying parameters on the morphology of nano-particles, homogeneous nano-particle heaps with a large aspect ratio were introduced to conventional layered coatings by plasma co-spraying with suspension and solid powder. Co-sprayed bimodal microstructure composite coatings resulted from both wet suspension droplets and molten particle droplets exhibited low thermal conductivity. The thermal conductivity of the composite coating was 1/5 lower than that of the counterpart coatings by conventional plasma spraying with solid powder. This study sheds light to the structural tailoring towards the advanced TBCs with low thermal conductivity.     

Influence of spraying conditions on thermal and velocity properties of plasma sprayed hydroxyapatite

Hydroxyapatite (HA), classified as a bioactive material, was proven to be well suitable for orthopaedic and dental applications due to its ability to integrate into bone structures and support bone ingrowth. Therefore it is used as a coating material for common metallic implant materials which carry most of the load. Covered by a layer of HA, the implants are much better accepted by surrounding tissues. To date, the only reliable method of applying HA coatings to metallic implants is plasma spraying. The aim of this research was to study the conditions to which the HA powder is exposed during spraying, which, in return, highly influence the resulting quality of the final coating. The two main characteristics describing and quantifying the plasma spraying process — temperature and velocity of the HA particles — were investigated. To study the changes of both characteristics under different spraying conditions, Taguchi design of experiment together with analysis of variance (ANOVA) method were utilized. Results showed the three main parameters influencing the powder particles' in-flight properties are gun power, main gas flow and spraying distance, while other parameters have a little (feed rate) or no effect (auxiliary gas).