等离子喷涂羟基磷灰石涂层的材料学特征

采用等离子喷涂技术,在钛合金基体表面制备羟基磷灰石涂层．使用ＸＲＤ和ＳＥＭ等测试手段,对获得的涂层进行了表征．结果表明,等离子喷涂过程中,同时发生羟基磷灰石的非晶化与热分解现象．热分解产物为ＣａＯ及α－Ｃａ_３（ＰＯ_４）_２．非晶化是高温羟基磷灰石液滴急剧冷却的结果．羟基磷灰石材料的热力学不稳定性,是发生热分解的主要原因．等离子喷涂获得具有一定粗糙度的羟基磷灰石涂层．涂层的显微结构中;存在气孔以及微裂纹．它们是等离子喷涂工艺的显微结构特征．羟基磷灰石涂层内部存在着烧结现象．涂层与金属基体之间的热传递性能变差,是导致烧结的主要原因．     

纳米ZrO2等离子涂层的结构,性能和工艺特点

采用大气等离子喷涂技术(APS)，制备了常规氧化锆和纳米结构氧化锆两种涂层．利用扫描电镜(SEM)对涂层的显微结构进行了观察．对两种涂层的沉积效率、表面粗糙度和显微硬度作了对比研究．结果表明，粉末原料的显微结构、粒度、形态、喷涂工艺参数(喷涂功率和距离)对涂层的显微结构有较大的影响．等离子喷涂造粒纳米氧化锆粉制备的涂层沉积效率高而稳定，其显微结构与喷涂功率和距离密切相关．与常规氧化锆涂层相比，纳米结构氧化锆涂层具有较高的显微硬度和较低的表面粗糙度．     

等离子喷涂碳化硼涂层相组成和电学性能研究

采用大气等离子喷涂,在不同喷涂距离下制备了碳化硼涂层,研究了喷涂距离对碳化硼涂层的显微结构、相组成和电导率的影响．用EDS和XPS分析了涂层的相组成;扫描电镜观察涂层的显微结构;标准四探针法测量涂层的电导率．结果表明,喷涂距离不仅会影响碳化硼涂层的显微结构,而且会改变碳化硼涂层的相组成;等离子喷涂碳化硼涂层的表面电导率随温度的增加而增加,表现出明显的半导体特性;涂层表面电导率同相组成和显微结构密切相关,涂层中B₂O₃相含量越高,气孔率越大,则涂层的电导率越低．     

纳米造粒料等离子喷涂氧化锆涂层的热物性研究

利用大气等离子喷涂技术和纳米粉体造粒料,制备了3mol%Y2O3部分稳定ZrO2热障涂层.利用扫描电镜(SEM)、透射电镜(TEM)研究了涂层的显微结构,采用差示扫描量热仪(DSC)、激光脉冲法热导仪对涂层的热物理性能进行了实验研究和理论分析.结果表明:利用纳米粉体造粒料和等离子喷涂技术可获得导热系数为0.63～0.80W/(m·K)的热障涂层.原因在于涂层显微结构中大量分布均匀的微小气孔和平均长度在十几微米的、垂直于热流方向的层状微裂纹.相变可导致涂层热物性变化异常.热处理后涂层的晶粒长大和气孔率降低可导致导热系数升高。     

HEPJet等离子喷涂Al2O3性能试验研究

研究了新开发的高效能超音速等离子喷涂系统(HEPJet-High Efficiency Plasma Jet)的射流特性,及所制备的Al2O3陶瓷涂层的结合强度、显微硬度和孔隙率等性能以及显微结构,并与一种普通等离子喷涂系统进行了对比试验研究.结果表明,HEPJet系统制备Al2O3涂层的性能及显微结构明显优于普通等离子喷涂的Al2O3涂层.     

MgAl2O4尖晶石涂层的显微结构

解XRD红外吸收光谱、ＴＥＭ和ＥＤＳ等方法研究了等离子喷涂尖晶石涂层的显微结构，结果表明，用等离子喷涂能获得结晶良好、阳离子分布比较有序的尖晶石涂层，涂层中尖晶石晶粒细小、均匀涂层热稳定性非常好，可在高温下长时间使用杂质可能导致涂层局部形成玻璃相涂层中尖晶石晶粒内存在大量位错，可能是在喷涂沉积过程中产生的变形所致     

低压等离子喷涂技术及研究现状

低压等离子喷涂作为一种热喷涂技术,相比于传统的大气等离子喷涂技术以及气相物理沉积,可制备更加纯净、更为致密、结合强度更高的涂层。主要介绍了低压等离子喷涂的原理、分类及特征,回顾了低压等离子喷涂的产生及发展历程,并与等离子喷涂、超低压等离子喷涂和等离子喷射沉积相比较,分析了其在涂层制备上的独特优势。进一步叙述了低压等离子喷涂技术在制备热障涂层、燃料电池、太阳能、半导体等领域的国内外研究及应用情况,并对其发展进行了展望,指出低压等离子喷涂技术未来的重点发展方向在于对等离子喷涂焰流与材料基板作用机理进行深入研究,以及与其他前沿技术进行复合。     

MgAl2O4尖晶石涂层的显微结构

用XRD，红外吸收光谱，TEM和EDS等方法研究了等离子喷涂尖晶涂层的显微结构，结构表明，用等离子喷涂能获得得结晶良好，阳离子体分布比较有序的尖晶石涂层，涂层中尖晶石晶粒细小，均匀，涂层热稳定性非常好，可在高渐下长时间使用，杂质可能导致涂层局部形成玻璃相，涂层中尖晶石晶粒内存在大量位错，可能在喷涂沉积过程中产生的主 所致。     

碳化硼涂层显微结构和性能研究

本文研究了碳化硼等离子喷涂涂层的显微结构和电导率．发现涂层中存在多种显微结构,颗粒状和板状的碳化硼相为主相;涂层中金属Ｆｅ杂质相的存在是涂层电导率出现异常的决定因素;碳化硼涂层中还发现了由Ｂ、Ｏ和Ｆｅ三种元素组成的杂质相,其显微硬度比碳化硼低,这是碳化硼涂层显微硬度同碳化硼陶瓷相比要低的一个重要原因．     

液相等离子喷涂制备纳米ZrO2/Y2O3涂层的研究

传统的喷涂技术制备的ZrO2/Y2O3涂层存在原料需团聚烧结致密,纳米晶粒不定和物理性能不佳等缺点.采用一种新型的液相等离子喷涂法制备了纳米氧化锆热障涂层,初步分析了液相前驱体液滴在等离子焰流中和基体表面的沉积变化过程,研究了雾化液滴尺寸对纳米氧化锆涂层的显微结构,特别是其相结构的影响;同时分析了纳米氧化锆涂层的抗热震循环性能.结果表明,纳米氧化锆涂层可以承受1 000多次的热循环试验,具有优良的抗热震性能.     

Preparation and properties of composite particles made by nano zinc oxide coated with titanium dioxide

In this paper, composite particles of nano zinc oxide coated with titanium dioxide were prepared and characterized by TEM, XRD, XPS and FT-IR, and the properties of the composite particles for photo catalysis and light absorption were studied. Tetrabutyl titanate (TBT) was hydrolyzed in an alcoholic suspension of nano zinc oxide with diethanolamine (DEA) as an additive, resulting in a film with a thickness of 20–30 nm being coated on the surface of nano zinc oxide, and the composite particles contained ZnTiO₃ after drying and calcination. Photocatalysis capabilities of the composite particles for the degradation of phenol in an aqueous solution were greatly improved as compared with nano zinc oxide particles before coating, with pure nano ZnO and nano TiO₂ with similar average sizes, or with the mixture of nano ZnO and TiO₂ with the similar composition as the composite particles. The light absorption scope of the composite particles was enlarged when compared to nano titanium dioxide with same average size.     

纳米ZrO_2粉体的热处理研究

用共沉淀法在不同热处理工艺下制备纳米ZrO2 粉体。样品的TEM、SAXS、BET和XRD分析结果表明 ,热处理对纳米ZrO2 粉体性能的影响是显著的。结合实验与理论分析 ,得出粉末颗粒长大、团聚的机制与热处理对成分、粒度及微观结构变化的作用     

钛合金表面微弧氧化纳米防污涂层及性能研究

利用微弧氧化技术,在Ti-6Al-3Nb-2Zr合金表面成功制备出纳米防污陶瓷涂层。采用扫描电镜、透射电镜和光学显微镜分析了纳米防污涂层的表面形貌、微观形态和氧化层厚度,采用X射线光电子能谱和X射线能谱仪对防污涂层的元素价态和化学组成进行了分析,采用WS-1型划痕试验机和数字万用表研究了涂层的结合强度和绝缘性,并采用TE66微磨损试验机和进行天然海水挂片试验考察了涂层的摩擦学性能和防污性能。结果表明:防污涂层厚度可达到20μm以上,涂层有非晶和20—50 nm纳米晶TiO2及Cu2O构成,膜基结合强度达到50 MPa,涂层绝缘性和耐磨性良好,防污性能得到明显改善,挂片6个月后涂层表面仅有少量海生物附着,而裸钛合金样品挂片3个月后则完全被海生物附着。     

纳米氮化钛粉体的制备及其影响因素

以纳米TiO₂为原料,采用氨气氮化法制备了纳米TiN粉体。研究了制备过程中的影响因素。实验结果表明:在800℃下,氮化反应5h,纳米TiO₂全部转化成纳米TiN,制备的纳米TiN粉体的粒径为20nm左右,采用化学分析法分析了纳米TiN的纯度,采用DTA-TG技术研究了纳米TiN的热稳定性。     

反应球磨钛与尿素制备氮化钛的反应机理研究

将Ti粉与尿素在室温下进行反应球磨制备了TiN粉末,对球磨不同时间后的粉末进行XRD分析,采用TG-FTIR技术分析了尿素的分解温度与产物,利用TEM及EELS观察和分析了球磨70h粉末的微观形貌、结构及成分. 结果发现,球磨70h合成了纳米TiN粉末,晶粒度为6~7nm,Ti/N原子比约为1.0∶0.6. 经800℃,5h真空退火处理后粉末的XRD谱图表明粉末组成为单相TiN. 在反应球磨过程中,Ti与尿素的分解产物NH₃与HNCO发生反应形成TiN,随球磨时间延长,Ti的缺陷能增大、活性增加,N在Ti中的扩散激活能减小,在球磨作用下N的扩散距离变短,TiN的含量逐渐增加形成晶核并逐渐长大形成纳米晶.     

用钨酸钠制备纳米钨粒子的研究

采用了两种技术路线制备纳米氧化钨粉。用透射电子显微镜研究了所制得的纳米氧化钨粒子的尺寸。研究结果表明,利用钨酸钠与盐酸诉反应可以得到纳米氧化钨粒子,粒子的尺寸在70～120nm之间。钨酸钠与盐酸反应在粘度更大的水解液中进行时,可以得到尺寸更小的氧化钨纳米粒子。对获得的氧化钨纳米粒子,在氢和碳气氛中、600℃下进行了还原处理,得到了纳米钨粉。与还原前的氧化钨粒子直径比较,纳米钨粉粒径在20～30nm之间,表明在含有碳气氛中还原氧化钨时,钨粒子生长速度慢。     

CERAMIC CARBIDE POWDER SYNTHESIS IN A NON-TRANSFERRED ARC PLASMA FLOW REACTOR

A method for the synthesis of fine, pure ceramic carbide powders such as silicon carbide, boron carbide and titanium carbide has been developed involving the thermal dissociation of silica, boron oxide or titanium oxide and methane in a thermal plasma, followed by the formation of the carbides in flight and rapid quenching. A non-transferred arc thermal plasma reactor has been designed, engineered, constructed and operated for this synthesis. The powders have been characterized chemically and physically. Thermodynamic calculations were performed to identify the appropriate experimental conditions and confirm the interpretations of the observed experimental results. A reaction mechanism is proposed based upon the experimental observations and results     

Preparation and characterization of selenium incorporated anodic conversion coatings on titanium surfaces for biomedical applications

An anodic spark deposition process was used for preparation of inorganic, glass-ceramic like conversion coatings. The microstructure of the layers was characterized by surface and solid state techniques such as scanning electron microscopy, electron probe microanalysis and Raman spectroscopy. The porous coatings, typically up to 8 μm thick, consist mainly of titanium oxides and amounts of incorporated electrolyte constituents like Se, Ca or P. Beside nano crystalline anatase phases, a mostly amorphous structure is proposed in which network-forming [PO₄] tetrahedras and [TiO₆] octahedras in various degrees of condensation are connected. A drastic modification of the film structure was observed when selenium was incorporated into the glassy oxide structure of the coating. In these cases no nano crystalline phases of titanium oxides or other chemical compounds were detected. First cell culture investigations show a significant improvement of the biological properties. Cell proliferation and TGF-beta-expression of these coatings in comparison with commercial pure titanium (CPT) with native titanium oxide films were examined.     

Microstructure and mechanical properties of spark plasma sintered titanium‐added copper/reduced graphene oxide composites

Copper matrix composites were fabricated through mixing fixed amount of reduced graphene oxide and the different amounts of titanium. The dried copper/titanium/reduced graphene oxide mixture powders were firstly obtained by the wet‐mixing process, and then the spark plasma sintering process realized their faster densification. In the as‐sintered bulk composites, the layered reduced graphene oxide network, uniform titanium particles and copper‐titanium solid solution are observed in copper matrix. Investigations on mechanical properties show that the as‐prepared bulk composites exhibit the hardness and compressive yield strength compared with single reduced graphene oxide added composites. Increased titanium addition resulted into higher hardness and strength. The relevant formation and failure mechanisms of the composites and their influence on mechanical properties were discussed.     

聚氮硅烷气相裂解反应制备Si-C-N复合纳米微粉的组成与结构

采用低分子聚氮硅烷气相裂解反应工艺 ,制备了Si C N复合纳米微粉。通过XRD、XPS、TEM、HREM等方法 ,对Si C N纳米微粉的组成与结构进行了分析。结果表明 :Si C N纳米微粉为无定形结构 ,局部有短程有序态存在。随裂解气氛的不同 ,Si、C、N元素的相对含量及存在状态也不同