反应热喷涂Al2O3.TiO2陶瓷涂层性能的研究

利用自蔓延高温合成原理(SHS)结合传统燃气喷涂技术,研究了反应热喷涂工艺制备的Al2O3.TiO2基金属陶瓷涂层的性能。结果表明,铝热反应热喷涂技术能够促进涂层性能的提高。涂层平均结合强度达17.50MPa以上,平均孔隙率降低到5.50%以下。     

铝电解用NiO-NiFe_2O_4基金属陶瓷的制备和性能研究

本文制备了数种NiO-NiFe_2O_4基金属陶瓷电极材料,找到了较优制备工艺参数和制粉工艺,着重测试了该金属陶瓷材料的导电率,分析了其导电机制,结果表明,采用化学镀铜比机械混合铜所得金属陶瓷的金属含量较少情况下导电率较佳,最后测定了该金属陶瓷用作铝电解惰性阳极的腐蚀速率。     

纳米Ti(CN)基金属陶瓷烧结过程中的相成分变化

采用在不同温度下真空烧结和X射线衍射研究纳米Ti(CN)基金属陶瓷在烧结过程中的相成分演变。研究结果表明:纳米Ti(CN)基金属陶瓷在900℃后,Mo2C和TaC由于扩散而发生固溶反应;在1 200℃前,Mo2C和TaC固溶反应结束,两相均消失;WC在1 100℃后,开始由于扩散而发生固溶反应,在1 250℃前消失;在1 250℃后,合金中只有Ti(CN)和Ni(Ni Co)两相存在;与纳米Ti(CN)基金属陶瓷不同,微米Ti(CN)基金属陶瓷中的WC在1 200℃后,由于扩散而发生固溶反应,在1 300℃消失;纳米Ti(CN)基金属陶瓷在固相反应完成之前,随着烧结温度的升高,硬质相和粘结相的晶格常数增加。     

Plasma preparation and low-temperature sintering of spherical TiC–Fe composite powder

A spherical Fe matrix composite powder containing a high volume fraction (82vol%) of fine TiC reinforcement was produced us-ing a novel process combining in situ synthesis and plasma techniques. The composite powder exhibited good sphericity and a dense struc-ture, and the fine sub-micron TiC particles were homogeneously distributed in theα-Fe matrix. A TiC–Fe cermet was prepared from the as-prepared spherical composite powder using powder metallurgy at a low sintering temperature;the product exhibited a hardness of HRA 88.5 and a flexural strength of 1360 MPa. The grain size of the fine-grained TiC and special surface structure of the spherical powder played the key roles in the fabrication process.     

Effect of Yb2O3 doping on the grain boundary of NiFe2O4–10NiO-based cermets after sintering

xYb2O3–15(20Ni–Cu)/(85?x)(NiFe2O4–10NiO) (x=0, 0.25, 0.5, 0.75, 1.0, 2.0, and 10.0) cermets for aluminum electrolysis were prepared to investigate the effect of Yb2O3 doping on the grain boundary of the cermets after sintering. The results showed that each interface was very clear and that with increasing Yb2O3 content, most of the Yb was evenly distributed at the grain boundary. Moreover, according to the phase composition and microstructural analysis by X-ray diffraction (XRD), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDX), and electron probe microanalysis (EPMA), YbFeO3 was produced along the grain boundary. The YbFeO3 was concluded to not only have formed from the interaction between the NiFe2O4 or Fe2O3 component and Yb2O3 at the grain boundary of the cermets, but also from the decomposition of NiFe2O4 into NiO and Fe2O3 and the subsequent reaction of Fe2O3 with Yb2O3. Thus, the pro-duction of YbFeO3 resulted in a cermet with high relative density, good electrical conductivity, and good corrosion resistance.     

金属陶瓷断裂韧性的价电子结构设计

依据固体分子经验电子理论,运用键距差方法,计算了不同成分金属陶瓷中陶瓷相的价电子结构,讨论了Ｍｏ、Ｗ、Ｎｂ、Ｔａ元素对陶瓷相价电子结构的影响,找出了金属陶瓷的断裂韧性与陶瓷相价电子结构之间的关系,据此推导出金属陶瓷的断裂韧性与其成分之间的关系式,并初步进行了实验验证     

Microstructure and properties of nano-TiN modified Ti（C,N）-based cermets fabricated by powder injection molding and die pressing

Powder injection molding （PIM） and die pressing were employed to fabricate nano-TiN modified Ti（C,N）- based cermets. The shrinkage behavior, microstructure, porosity, and mechanical properties of the samples with and without nano-TiN addition fabricated by PIM and die pressing were analyzed. It is demonstrated that for either PIM or die pressing, the porosities are obviously reduced, the mechanical properties are significantly improved after adding nano-TiN, and the hard particles are refined; the rim phase thickness obviously becomes thinner, and the number of dimples in fracture also increases. Compared the samples fabricated by die pressing, it is difficult for PIM to obtain dense Ti（C,N）-based cermets. Due to the too much existence of pores and isolated carbon, the mechanical properties of the sintered samples by PIM are inferior to those of the sintered ones by die pressing.     

三元硼化物基金属陶瓷复合材料及其液相烧结机理

三元硼化物基金属陶瓷是性能优异的新型复合材料,三元硼化物基金属陶瓷复合材料的制备工艺、性能特点、氧、碳及其它合金元素对材料制备和材料性能的影响以及材料的液相烧结机理被综合评述。     

烧结温度对细晶粒Ti(C,N)基陶瓷组织和性能的影响

采用真空烧结工艺制备超微、纳米复合Ti(C，N)基金属陶瓷．研究了烧结温度对超微、纳米复合Ti(C，N)基金属陶瓷的显微组织、性能的影响，并用SEM观察试样的断口形貌．结果表明，随着烧结温度的升高，陶瓷材料的显微组织逐渐变得均匀致密，晶粒长大不明显，环形相逐渐变得完整；当烧结温度超过1450℃，晶粒会明显长大，环形相变厚、变脆，导致材料的性能下降．进一步分析表明，超微和纳米复合Ti(C，N)基金属陶瓷的最佳烧结温度分别为1410℃、1450℃．     

Al2O3/WC-10Co/ZrO2金属陶瓷的制备与性能

以WC-10Co纳米复合粉末、YSZ纳米粉末与Al2O3亚微粉末为原料,采用热压烧结制备了性能优良的Al2O3/WC-10Co/ZrO2金属陶瓷.分别在1380,1450和1500℃烧结温度下制备Al2O3/WC-10Co/ZrO2金属陶瓷,通过考察烧结体的断裂韧性、洛氏硬度、密度、磁滞回线和断口形貌,研究了烧结温度对WC-10Co纳米复合粉末、YSZ纳米陶瓷粉末与Al2O3亚微粉末的复合粉末烧结性能的影响.确定合理的Al2O3/WC-10Co/ZrO2金属陶瓷烧结温度为1450℃.结果表明,质量分数为50%的WC-10Co纳米复合粉末、10%的YSZ纳米陶瓷粉末与和40%的亚微Al2O3粉末的复合粉末经过48h的高能球磨后,再经过1450℃热压烧结,可以得到晶粒尺寸小于1μm的整体性能较好的亚微Al2O3/WC-10Co/ZrO2金属陶瓷,其相对密度为97.5%,断裂韧性为7.4468MPa·m1/2,硬度为HRA 94.0.