电化学沉积法制备钛基HA涂层

在钛基材表面获得羟基磷灰石（HA）涂层以改善钛与生物体的相容性，本项工作采用电沉积的方法在阳极氧化处理过的钛基体上制备了羟基磷灰石涂层。用扫描电子显微镜（SEM）、X射线衍射（XRD）等手段对涂层进行了表征。试验结果表明：电沉积初期的羟基磷灰石涂层呈多孔层片状：随电压、时间、电解液浓度的增大，涂层变厚，层片呈花瓣状发散排列：对基体阳极氧化处理有助于提高钛基与涂层的结合强度。     

微弧氧化和碱处理对钛的细胞黏附和骨植入行为的影响研究

海南大学与南京理工大学的科研工作者联合考察了微弧氧化处理和碱处理对钛表面形貌、涂层成分、羟基磷灰石沉积能力、细胞黏附性、骨内植入效果的影响。结果表明,经微弧氧化和碱复合处理后,钛表面TiO2薄膜呈现大量裂缝,表现出表面含大量OH-极性基团的纳米多孔网状结构,此微观结构和组成使材料诱导羟基磷灰石生成能力显著,利     

钛合金表面声电沉积/碱热处理法制备HA涂层研究

为了使钛合金(Ti-6Al-4V)具有生物活性,可在其表面施加生物活性羟基磷灰石(HA)涂层.对比了声电沉积法和碱热处理法实验结果,采用扫描电镜(SEM)、X射线衍射仪(XRD)、电子能谱(EDS)、傅立叶红外透射光谱(FTIR)以及划痕测试等进行了分析.结果表明,直接采用声电沉积法在钛合金表面制备的羟基磷灰石涂层,经热处理后存在龟裂剥落现象;通过碱热处理法,对钛合金基体表面进行预处理,然后,借助声电沉积法,在钛金属表面沉积了透钙磷石涂层,经热碱液处理转变成的羟基磷灰石涂层,涂层完整,未出现剥落.经进一步高温烧结处理,所制涂层仍呈片状形貌,其由部分含钠的羟基磷灰石组成,而且HA涂层破坏的临界载荷未烧结前的4.365 N提高至烧结后的8.175N.     

Si基上羟基磷灰石/Al2O3复合生物涂层的制备

采用物理气相沉积(PVD)与阳极氧化与电沉积相结合的复合技术在Si基表面制备了羟基磷灰石(HA)/Al2O3复合生物涂层。采用SEM研究了阳极氧化Al2O3和HA/Al2O3复合生物涂层的形貌,并采用EDS与XRD研究了HA/Al2O3复合生物涂层的组成和物相。结果表明:扩孔处理后阳极氧化的Al2O3孔径约为1.5~3.0μm,电沉积HA的n(Ca)/n(P)约为1.61,最终获得了以HA为外层、HA/Al2O3为中间过渡层、Si为基底的复合材料。其中,HA不仅沉积于阳极氧化Al2O3的孔洞中,且外延生长并覆盖在阳极氧化Al2O3表面,从而在HA外层与HA/Al2O3中间过渡层之间形成了一种T形分布的结构特征,该结构特征将有助于增强HA外层与中间过渡层的界面结合强度。     

碳/碳复合材料表面声电沉积/碱热处理复合工艺制备羟基磷灰石生物活性涂层研究

通过碱热处理工艺对碳/碳复合材料表面阴极声电沉积的磷酸钙生物陶瓷涂层进行处理,使其转变为磷灰石涂层,采用SEM,EDAX,FTIR,XRD等研究了涂层组成、结构和形貌的变化,并采用拉伸测试评价了涂层与基体的结合力,用SEM观察了涂层的断口形貌.结果表明：用声电沉积技术获得的片状透钙磷石涂层经碱热处理后而得到磷灰石涂层,涂层与基体形成了化学键合,且结合紧密,涂层的形貌没有显著变化,但涂层的致密度有所增加;拉伸测试表明涂层与基体的结合强度最大可达4.2 MPa 以上,涂层的失效部位主要在涂层内部,其失效方式为涂层的内聚破坏和界面脱粘.     

医用Ti84Mo16合金表面改性研究

基于表面活性涂层培养目的,选择粉末冶金工艺制备微孔态Ti84Mo16合金基体.基体进行热处理和碱处理,进而浸入人体模拟液中进行活性涂层沉积.实验结果表明;经过四周培养,钛钼合金表面能够成功培养出类骨涂层——羟基磷灰石Ca10(PO4)6(OH)2,这为解决钛合金植入物和人体组织之间结合力不足的问题提供了一个非常有效的途径.     

钛生物种植体表面羟基磷灰石生成技术发展现状

总结了现有钛生物种植体表面羟基磷灰石生成技术及其优缺点;并针对钛生物种植体表面羟基磷灰石涂层在制备过程中存在的界面结合强度低、涂层内的残余应力以及膜层中羟基磷灰石(HA)的分布密度等问题,进行归纳总结。     

脉冲电沉积涂覆纳米羟基磷灰石的多孔Mg-Zn支架材料的体外生物降解能力和生物相容性(英文)

研究纳米羟基磷灰石(HAP)涂覆的多孔Mg-2Zn(质量分数,%)支架材料的生物降解能力和生物相容性。采用脉冲电沉积制备羟基磷灰石涂层。对涂覆HAP的支架在碱性溶液中进行后处理来改善其生物降解性和生物相容性。研究支架和HAP涂层的显微组织和成分以及它们在模拟体液(SBF)中的降解和细胞毒性。经过碱溶液处理后的涂层由几乎垂直于基体的直径小于100 nm的针状HAP组成,具有和天然骨头相似的成分,浸泡在SBF中后,产物为HAP、(Ca,Mg)3(PO4)2和Mg(OH)2。涂覆HAP和经过处理碱处理后的支架比未涂覆HAP的支架具有更高的生物相容性和细胞存活性。MG63细胞粘附在涂覆HAP和经过碱处理后的支架的表面并增殖,使这些支架有望应用于医学。结果表明:纳米HAP的脉冲电沉积和碱处理可有效改善多孔Mg-Zn支架的生物降解能力和生物相容性。     

溶胶凝胶法制备TiO_2/HA复合生物活性涂层及其体外活性

通过溶胶凝胶法在纯钛基体上制备了羟基磷灰石(HA)/TiO2复合生物活性涂层。HA和TiO2溶胶由前驱体制得,按不同摩尔比直接混合两种溶胶来制备混合溶胶。HA可以提高钛基的生物活性,TiO2可以提高涂层与基体的物理、化学相容性和结合强度。粘结拉伸结果表明,复合涂层与基体结合良好,比纯HA涂层与基体的结合强度提高约47%。复合涂层试样于SBF中浸泡4、7和14d的SEM分析结果表明,复合涂层表面的类骨磷灰石生成量较高。成骨细胞实验结果表明,复合涂层上细胞铺展良好。     

AZ91镁合金表面电化学沉积羟基磷灰石涂层的制备及其耐蚀性

采用电化学沉积方法在AZ91镁合金表面制备了羟基磷灰石(HA)涂层,研究了电沉积工艺参数对羟基磷灰石涂层形貌和相组成的影响,并通过腐蚀浸泡试验、极化曲线测试等方法对该涂层的耐蚀性进行了研究。结果表明:当溶液pH为4.5,温度为60℃时,涂层的致密性最好,呈放射状的结构,主要成分为HA相,涂层的厚度约为60~70μm,与基体结合较好;HA涂层对镁合金基体具有较好的保护作用,显著提高了基体合金在生理溶液中的耐蚀性。     

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.     

Sol–gel derived hydroxyapatite coatings on titanium substrates

The oscillatory micromovements at the interface between the implant and the bone induce fretting wear and sometimes, fatigue cracks, causing early failure of the joint prosthesis. Hydroxyapatite films were formed using a sol–gel method from an organic precursor solution. The average film thickness was found to be 1.0 μm. Composite coatings containing HA doped with ZrO₂ were also formed. Hydroxyapatite (HA) and composite films of HA and ZrO₂ formed on commercial titanium substrates using an organic precursor solution by sol–gel route, were tested for fretting wear using a ball-on-flat fretting apparatus. The moderately lower values of the coefficient of friction (0.4–0.5) and morphology of the wear pits for considerably long cycles of fretting indicate strong bonding of the HA coating to the titanium surface. The interface shear strength of a thin hydroxyapatite film on commercial purity titanium has been evaluated using a substrate straining method. The maximum interfacial strength was about 570 and 678 MPa, for the pure HA and composite films, respectively, on the highly polished surface. However, the maximum interfacial strength was found to be about 263 MPa on the oxidized surface.     

Preparation and characterization of silicon-substituted hydroxyapatite coating by a biomimetic process on titanium substrate

A biomimetic method has been used to prepare silicon-substituted hydroxyapatite coatings on titanium substrates. The surface structures of the coatings were characterized by X-ray diffraction, X-ray photoelectron spectroscopy (XPS) and Fourier transformed infrared spectroscopy (FTIR). Si substituted hydroxyapatite (Si-HA) coatings with different Si contents were deposited successfully on the titanium substrate by immersing the pretreated titanium substrate into silicon containing supersaturated solutions (SSS) with different SiO₃²⁻ concentrations. The pretreatment of the Ti substrate in a mixed alkaline (NaOH + Ca(OH₂)) followed by a heat treatment produced a 3D porous surface structure with rutile and CaTiO₃ as main phases, which contributed mainly to the fast precipitation and deposition of Si-HA. FTIR results showed that Si in the Si-HA coating existed in the form of SiO₄⁴⁻ groups. The cross-section microstructure was observed by scanning electronic microscopy and the shear strength was tested. The coating was about 5-10 μm in thickness and no interval was observed at the interface between the coating and the substrate. Shear strength testing showed that Si-HA/Ti exhibited higher shear strength than HA/Ti due to the existence of the SiO₄⁴⁻ group in the coating.     

HA coating on titanium with nanotubular anodized TiO2 intermediate layer via electrochemical deposition

Hydroxyapatite（HA） coating has been prepared on titanium substrate through an electrochemical deposition approach. In order to improve the bonding strength between HA coating and Ti substrate, a well oriented and uniform titanium oxide nanotube array on the surface of titanium substrate was applied by means of anodic oxidation pre-treatment. Then the calcium hydrogen phosphate（CaHPO4·2H2O, DCPD） coating, as the precursor of hydroxyapatite coating, was electrodeposited on the anodized Ti. At the initial stage of electro-deposition, the DCPD crystals, in nanometer precipitates, are anchored in and between the tubes. With increasing the deposition time, the nanometer DCPD crystals are connected together to form a continuous coating on titanium oxide nanotube array. Finally, the DCPD coating is converted into hydroxyapatite one simply by being immersed in alkaline solution.     

Influence of deposition temperature on mechanical properties of plasma-sprayed hydroxyapatite coating on titanium alloy with ZrO<Subscript>2</Subscript> intermediate layer

Hydroxyapatite coatings were plasma sprayed on the Ti6A14V substrate with and without an intermediate ZrO₂ layer; meanwhile the temperatures of substrates were varied at 90, 140, and 200 °C. The coatings were subjected to the standard adhesion test per ASTM C633-79. The purpose of the investigation was to study the effects of those processing variables on the bonding strength and failure behavior of the system. It is found that the bonding strengths of HA/ZrO₂ and HA coatings generally decrease with increasing substrate temperature, except for the HA/ZrO₂ coating deposited at 200 °C. The rationale of the results is attributed to the residual stress reported in the literature. Introducing ZrO₂ bond coat is found to significantly promote the bonding strength of HA coating. The possible strengthening mechanism is the rougher surface of ZrO₂ bond coat and the higher toughness of ZrO₂, which provide the mechanical strengthening effects. The slightly denser HA in 200 °C deposited HA coating cannot explain the high bonding strength of the HA/ZrO₂ coating, nor the mechanical strengthening effect of ZrO₂ intermediate layer should apply. It is believed that a stronger diffusion bonding is formed at the interface of HA and ZrO₂, which increases the bonding between them chemically. The bonding strengths of HA/ZrO₂ and HA coatings are correlated with the area fraction of adhesive failure of the coatings. The correlation explains the findings in this study.     

Characterization, Corrosion Resistance, and Cell Response of High-Velocity Flame-Sprayed HA and HA/TiO2 Coatings on 316L SS

The main aim of this study is to evaluate corrosion and biocompatibility behavior of thermal spray hydroxyapatite (HA) and hydroxyapatite/titania bond (HA/TiO₂)-coated 316L stainless steel (316L SS). In HA/TiO₂ coatings, TiO₂ was used as a bond coat between HA top coat and 316L SS substrate. The coatings were characterized by x-ray diffraction and scanning electron microscopy/energy dispersive spectroscopy, and corrosion resistance determined for the uncoated substrate and the two coatings. The biological behavior was investigated by the cell culture studies using osteosarcoma cell line KHOS-NP (R-970-5). The corrosion resistance of the steel was found to increase after the deposition of the HA and HA/TiO₂ bond coatings. Both HA, as well as, HA/TiO₂ coatings exhibit excellent bond strength of 49 and 47?MPa, respectively. The cell culture studies showed that HA-coated 316L SS specimens appeared more biocompatible than the uncoated and HA/TiO₂-coated 316L SS specimens.     

Fabrication of calcium phosphate/chitosan coatings on AZ91D magnesium alloy with a novel method

Four calcium phosphate/chitosan composite films were fabricated on the surface of micro-arc oxidized (MAO)-AZ91D alloy through electrophoretic deposition (EDP) followed by a conversion process of the coatings in a phosphate buffer solution (PBS). In the EPD process, nano hydroxyapatite (n-HA, Ca₁₀(PO₄) ₆(OH)₂) and Ca(OH)₂ in the layers were obtained from a n-HA/ethanol suspension and a n-HA/chitosan-acetic acid aqueous solution, respectively. After immersion into PBS, brushite (DCPD, CaHPO₄·2H₂O) and new HA were introduced into the deposited layers. The percentage of Ca(OH)₂ in the deposited layers played an important role in developing the new phase in the conversion layers. When the percentages of Ca(OH)₂ in the deposited layers were 32 wt. % and 54 wt. %, the main phase of the conversion layers was DCPD with a little HA. However, when the percentages of Ca(OH)₂ were 64 wt. % and 100 wt. %, the main phase of the conversion layers became HA with a little DCPD. The calcium phosphate/chitosan coatings with more homogeneous bioactive layers and better adhesion strength on MAO-AZ91D alloy substrate were obtained from the electrolyte whose volume percentages of the n-HA/chitosan-acetic acid aqueous solution being 60% and 80%.So, EPD combined with a conversion process into PBS could be a promising method for the preparation of new calcium phosphate/chitosan coatings.     

Hydroxyapatite coating on pretreated CoNiCrMo prosthesis

1 INTRODUCTIONCo-alloys arei mportant metallic medical mate-rials for tribologically loaded knee , hip joints andtheir fixation parts ,as shownin Fig.1 ,due to ex-cellent mechanical , tribological and corrosion-resistant properties[1]. A bioactive ceramic coat-ings ,especially hydroxyapatite( HA) coating, onmetallic prostheses is a promising approachfor i m-proving its osteoconductivity and bone-bondingability[2 11]. Nowadays ,some plasma sprayed HAand other bioceramic coatings on metall…     

HVOF-Sprayed Nano TiO2-HA Coatings Exhibiting Enhanced Biocompatibility

Biomedical thermal spray coatings produced via high-velocity oxy-fuel (HVOF) from nanostructured titania (n-TiO₂) and 10 wt.% hydroxyapatite (HA) (n-TiO₂-10wt.%HA) powders have been engineered as possible future alternatives to HA coatings deposited via air plasma spray (APS). This approach was chosen due to (i) the stability of TiO₂ in the human body (i.e., no dissolution) and (ii) bond strength values on Ti-6Al-4V substrates more than two times higher than those of APS HA coatings. To explore the bioperformance of these novel materials and coatings, human mesenchymal stem cells (hMSCs) were cultured from 1 to 21 days on the surface of HVOF-sprayed n-TiO₂ and n-TiO₂-10 wt.%HA coatings. APS HA coatings and uncoated Ti-6Al-4V substrates were employed as controls. The profiles of the hMSCs were evaluated for (i) cellular proliferation, (ii) biochemical analysis of alkaline phosphatase (ALP) activity, (iii) cytoskeleton organization (fluorescent/confocal microscopy), and (iv) cell/substrate interaction via scanning electron microscopy (SEM). The biochemical analysis indicated that the hMSCs cultured on n-TiO₂-10 wt.%HA coatings exhibited superior levels of bioactivity than hMSCs cultured on APS HA and pure n-TiO₂ coatings. The cytoskeleton organization demonstrated a higher degree of cellular proliferation on the HVOF-sprayed n-TiO₂-10wt.%HA coatings when compared to the control coatings. These results are considered promising for engineering improved performance in the next generation of thermally sprayed biomedical coatings.     

The influence of Si as reactive bonding agent in the electrophoretic coatings of HA–Si–MWCNTs on NiTi alloys

In this study, different composite coatings with 20 wt.% silicon and 1 wt.% multi-walled carbon nanotubes of hydroxyapatite were developed on NiTi substrate using a combination of electrophoretic deposition and reactive bonding during the sintering. Silicon was used as reactive bonding agent. During electrophoretic deposition, the constant voltage of 30 V was applied for 60 s. After deposition, samples were dried and then sintered at 850 °C for 1 h in a vacuum furnace. SEM, XRD and EDX were used to characterize the microstructure, phase and elemental identification of coatings, respectively. The SEM images of the coatings reveal a uniform and compact structure for HA–Si and HA–Si–MWCNTs. The presence of silicon as a reactive bonding agent as well as formation of new phases such as SiO₂, CaSiO₃ and Ca₃SiO₅ during the sintering process results in compact coatings and consumes produced phases from HA decomposition. Formation of the mentioned phases was confirmed using XRD analysis. The EDX elemental maps show a homogeneous distribution of silicon all over the composite coatings. Also, the bonding strength of HA–Si–MWCNTs coating is found to be 27.47 ± 1 MPa.