The Study on the fabrication of self-lubricant ceramics with high-hardness and surface modification of metals by their ceramics.

我们尝试制备由过渡金属氮化（TiN或ZrN）基体和六方氮化硼（h-BN）分散体组成的自润滑复合陶瓷。混合粉末用行星球磨机研磨不超过180k。混合粉末的x射线衍射图表明，h-BN粉末被磨成小于亚微米的细粉，并在36ks以上的时间内分散。采用脉冲电流压力烧结（ppps）方法对混合粉末进行固结。ZrN + 5mass % h-BN粉末烧结180ks后，获得了相对较高的密度固结率90%以上的单一ZrN（或TiN）粉末。BN添加量大于5质量%时，烧结坯的硬度降低。结果表明，h-BN的加入能明显抑制混合粉末的烧结。采用球盘式摩擦试验装置，对复合陶瓷烧结试样与SUJ-2钢球进行了摩擦试验，通过摩擦系数的演化来评价烧结试样的摩擦学特性。在ZrN基体中添加5%的h-BN，摩擦系数显著降低至0.2左右，防止了粘着磨损。与ZrN-5质量% h-BN混合粉末相比，ZrN-5质量% h-BN混合粉末烧结后的摩擦系数较低，烧结时间为180ks的2倍。然而，在纳米尺度范围内，更细的h-BN颗粒分散是维持较长时间自润滑效果的必要条件。采用反应溅射法制备了Cr-B、Cr-B- n和Cr-B/Cr-B- n多层膜。Cr-B-N膜中含有Cr2B和h-BN相，其他相较少。Cr-B/Cr-B- n多层膜的摩擦系数介于Cr-B（0.9）和Cr-B- n（0.2）之间，中间值为~ 0.45。

We tried to fabricate self-lubricant composite ceramics consisting of transition metal nitride (TiN or ZrN) matrixes and hexagonal boron nitride (h-BN) dispersions. Mixture powders were milled with a planetary ball mill for not more than 180ks. Xray-diffraction patterns for the mixed powder showed that h-BN powder was finely grounded smaller than a submicron level and dispersed by the milling for longer than 36ks. The pulse current pressure sintering (PCPS) method was employed in order to consolidate the mixed powders. Relatively high density consolidation of more than 90% for single ZrN (or TiN) compact was obtained from the sintered compact of ZrN + 5mass % h-BN powders milled for 180ks. The hardness of the sintered compacts decreased with the addition of BN of more than 5 mass%. This result suggests that the sintering of mixed powder could be strongly inhibited by the addition of h-BN.Sliding friction tests between sintered compacts of composite ceramics and SUJ-2 steel ball were performed using a ball-on-disc apparatus, in order to estimate the tribological characteristics of sintered compacts by the friction coefficient evolution. Only a 5% addition of h-BN into the ZrN matrix showed a marked decrease in the friction coefficient to about 0.2, preventing adhesive wear. The sintered compact of ZrN-5 mass% h-BN powders milled for 180ks maintained low friction coefficient for two-times longer compared to the sintered compact of ZrN-5 mass% h-BN mixed powders. However, finer dispersion of h-BN particle under the range of nanometer size is essential to sustain the self-lubricant effect for longer time to be practical.Cr-B, Cr-B-N and Cr-B/Cr-B-N multilayer films were synthesized by reactive sputtering. Cr-B-N films contain Cr2B and h-BN phase with a small amount of other phases. Friction coefficient of Cr-B/Cr-B-N multilayer exhibited an intermediate value of 〜0.45 between those of Cr-B (0.9) and Cr-B-N (0.2).