Kinetics of TiB_2 Grain Growing During HP-Sintering

It was reported that TiB2 gains grew fast during sintering was a main cause for its properties degrading. In this paper the HP-sintering mechanics of TiB2 was studied and the results show that grains grow very fast when the sintering temperature is near 1800℃ . From the sintering dynamics, it can be concluded that grain fast growing results in boundary-transporting processing, during which grain boundary work as fast tunnel for material transporting.     

Combustion Synthesis of the Titanium-Aluminum-Boron System

TiB₂ and Al base composite powders, which will offer a weight-saving improvement in stiffness, were produced by combustion synthesis of Ti, Al, and B ternary powder mixtures. Finely dispersed TiB₂ was synthesized by reacting a mixture of Ti, Al, and B in the molar ratio of 1:1:4. The grain size of the TiB₂ formed was <0.5 μm, which was much smaller than that obtained from the reaction of a mixture of Ti, Al, and B in the molar ratio 1:1:2. These results are discussed in light of the reaction propagating velocity and heat removal during the combustion synthesis process.     

偏压对磁控溅射制备Ni掺杂TiB2基涂层结构及力学性能的影响

采用双靶非反应磁控溅射,通过改变基底偏压,制备了一系列Ni掺杂TiB2基的涂层.通过X射线能谱仪确定其成分,利用X射线衍射、扫描电镜对涂层的结构进行分析,并通过纳米压痕、维氏压痕、划痕以及摩擦磨损分别对涂层的硬度、模量、断裂韧性、膜基结合力和摩擦学性能进行了表征.结果表明:此工艺下制备的TiB2-Ni涂层中均存在六方相的TiB2结构,并且生长结构非常致密,无明显的柱状生长结构,表面粗糙度低;硬度均大于40 GPa;涂层均具有较好的断裂韧性;且随着偏压增大断裂韧性和结合力都有所提高;同时所制备涂层摩擦系数均在0.5～0.6,磨损率在同一数量级.     

TiB_2含量对原位反应合成TiB_2/B_4C复合材料的组织结构和力学性能的影响(英文)

以B4C,TiO2和石墨粉为原料,采用原位反应热压烧结工艺(2050℃,35MPa,1h)制备了致密的TiB2含量为10%～40%(体积分数)的TiB2/B4C复合材料,并对复合材料的组织结构和力学性能进行了研究。扫描电子显微镜和透射电子显微镜分析结果表明:在B4C晶内及晶界处均匀分布着纳米或亚微米级的TiB2颗粒,随着TiB2含量的增加,弹性模量和断裂韧性明显增大,而弹性模量和抗弯强度却随之减小。40%(体积分数)TiB2/B4C复合材料具有高的断裂韧性,高达8.2MPam1/2,主要增韧机制由微裂纹增韧和裂纹偏转增韧。     

真空度对TiB2/Al复合材料摩擦行为的影响（英文）

在不同真空度条件下(0.01、0.03、0.05、0.07和0.1MPa),采用销盘式摩擦磨损试验机研究气压对TiB2/Al复合材料的摩擦学行为的影响。结果表明:随着气压的增加,摩擦系数呈现下降的趋势,而磨损率变化不大。能谱分析表明,随着真空度的升高,磨损表面的Fe含量逐渐下降,与摩擦系数的下降趋势保持一致。     

稀土对TiB_2/7055复合材料组织及性能的影响

采用K2TiF6和KBF4混合盐原位反应法制备TiB2/7055复合材料,研究了稀土对复合材料铸态组织和力学性能的影响。结果表明：添加0.3%稀土可以显著细化复合材料的铸态组织,晶粒尺寸从200μm减小到40μm左右。同时,TiB2颗粒得到细化,其平均尺寸约为100 nm;TiB2颗粒在基体上的分布也更加均匀。经过480℃固溶60 min、120℃时效24 h后复合材料抗拉强度达到690 MPa,伸长率达到5.5%。     

TiB/Ti基金属陶瓷燃烧合成反应热力学

为了解Ti-B二元体系的自蔓延合成反应进行的方向和最终产物的相组成，对Ti-B二元体系燃烧合成反应生成TiB的自由焓变、自由能、反应绝热温度和燃烧温度进行了理论分析和实验研究。结果表明，Ti含量过量的情况下TiB的反应生成自由焓比TiB2的反应生成自由焓高，反应生成自由能比TiB2的更低，TiB在生成热力学上比TiB2更稳定，Ti与B的SHS反应更易生成TiB相，Ti-B二元体系的反应绝热温度和燃烧温度随着Ti含量的提高而呈下降趋势。     

Tube-in-Basket burner for rice husk. I: Properties of husk as a fuel and basic design considerations

Rice husk, the main by-product of milling paddy, is one of the more easily available and abundant renewable energy resources. None of the husk combustion systems available at present is suitable for those who have relatively modest energy requirements and whose options in the matter of alternate energy sources are limited and costly. Decentralised post-harvest processing and small scale rural industries are examples. The Tube-in-Basket (TiB) husk burner described here is a compact, simple and easy-to-fabricate device, which produces a clean and concentrated flame with high combustion efficiency. As a low cost heat module, using an agro-residue as fuel, TiB holds promise of contributing towards meeting the energy demand of the rural segment of society in the underdeveloped countries. Part I of this communication deals with rice husk, its combustion characteristics, and some pertinent aspects of the existing husk combustion systems. It then describes the design criteria for TiB taking into account the properties of husk as a fuel. Performance data of a prototype batch TiB is included to demonstrate the validity of the basic design. For correspondence.     

TiC+TiB_2颗粒增强Fe基激光熔覆层的组织与性能研究

采用钛铁、碳化硼、铁粉等组分,利用激光熔覆技术制备原位自生TiC+TiB2颗粒增强Fe基熔覆层。利用金相显微镜、X射线衍射仪、电子探针及显微硬度计,研究了熔覆层的显微组织与性能。研究结果表明,激光熔覆层于低碳钢基体呈冶金结合,熔覆层致密、无孔隙。原位生成的块状或花瓣状的TiC和条状TiB2均匀的分布在基体中,熔覆层具有较好的硬度和良好的耐磨性。