含氧超细TiN0.3粉体与烧结体的制备及氧对其组织结构的影响研究

Preparation of Oxygen-Containing Ultrafine TiN Powder and Sintered Body and Effects of Oxygen on Their Microstructures

采用机械合金化(MA)法制备了平均晶粒尺寸约10 nm的超细TiN0.3粉体,分别采用机械合金化(MA)、空气中热处理、高压高温(HPHT)烧结、退火处理4种方式向TiN0.3粉体中引入氧,研究氧引入量对TiN0.3粉体及烧结体的物相组成、晶粒尺寸及晶格常数的影响。结果表明,空气中热处理氧引入量最多,而MA、真空退火处理、HPHT烧结过程氧引入量较少。MA、退火处理、空气中热处理过程氧引入量少时均会因TiNxOy的生成而导致晶格常数增大。MA过程氧的引入降低了球磨效率而导致晶粒尺寸增大,退火过程氧引入前后晶粒尺寸无明显变化。TiN0.3粉体在空气中的起始氧化温度和终止氧化温度分别为315.6℃和654.1℃。TiN0.3粉体起始氧化产物为TiNxOy,360℃时生成A-TiO2(锐钛矿型TiO2),同时开始向R-TiO2(金红石型TiO2)转变。700℃时A-TiO2已完全转变为R-TiO2。

The ultrafine TiN0.3 powder with an average grain size of about 10 nm was prepared by mechanical alloying(MA) method. Four methods, including mechanical alloying(MA), heat treatment in the air, high pressure and high temperature(HPHT) sintering, and annealing treatment, were used to introduce oxygen into TiN0.3 powder, and the influence of oxygen introduction on the phase composition, grain size and lattice constant of TiN0.3 powder and sintered body was investigated. The results show that heat treatment in the air needs the highest oxygen inflow, while MA, vacuum annealing and HPHT sintering processes needs lower oxygen inflow. When the oxygen inflow is lower during MA, annealing and heat treatment in air, the lattice constant increases due to the formation of TiNxOy. The oxygen introduction in the MA process reduces the ball milling efficiency and leads to the coarser grains, but there is no significant difference in the grain size before and after the introduction of oxygen in the annealing process. The initial and final oxidation temperature of TiN0.3 powder in air are 315.6 ℃ and 654.1 ℃, respectively. The initial product from oxidation of TiN0.3 powder is TiNxOy. At 360 ℃, A-TiO2(anatase type TiO2) is formed and the transformation to R-TiO2(rutile type TiO2) begins. At 700 ℃, A-TiO2 has been completely transformed into R-TiO2.