【作者】 任玉铎；

【导师】 王明智；

【作者基本信息】 燕山大学 ， 材料学， 2010， 硕士

【摘要】 CrN具有许多优异的物理和化学性能,比如其优异的耐磨性和其他过渡金属氮化物不具备的反铁磁性,加热处理时分解出的高活性的N也可以作为氮源提高某些金属烧结体的性能。然而由于Cr的活性较低,制备立方结构的CrN很困难且CrN的脆性较高,对其烧结体的研究也非常少。因此简化其合成方法具有非常重要的理论和现实意义。本论文以球磨的方法制备非化学计量比的CrN_x粉末,并将制备的CrN_x粉末进行SPS烧结,研究了不同温度下制备的烧结体的性能。以Cr₂N和Cr为原料进行球磨制备非化学计量比的CrN_x,利用X射线衍射（XRD）、差热分析仪（DSC）和扫描电子显微镜（SEM）对球磨后粉体进行结构分析和形貌观察。将球磨制备的CrN_x粉末在不同烧结温度条件下进行SPS烧结,对烧结体的断口进行SEM观察,并对烧结体的机械性能进行测试。通过粉体结构分析得出:相同球磨时间的条件下,随着Cr含量的增加,CrN_x的晶粒先变大,后减小;加热处理后分解N₂逐渐增大。相同原料配比的条件下,随着球磨时间的增加,CrN_x晶粒逐渐变小,加热处理后分解N₂逐渐增大。通过粉末形貌观察得出:相同球磨时间的条件下,随着Cr含量的增加,粉体颗粒均存在颗粒团聚的情况,颗粒度先变大后减小;相同原料配比的条件下,随着球磨时间的增加,粉体颗粒度逐渐变小,最终达到平衡。通过烧结体结构和性能分析得出:随着烧结温度的增加,烧结体晶粒度逐渐减小,烧结体的致密度、硬度、抗折强度增加。Cr₂N与Cr按1:0.5摩尔比混合,经50h球磨处理后的CN5粉末,在1100℃和40 MPa条件下得到烧结体的硬度、致密度和抗折强度分别达到22.09GPa、99.5%和239.1MPa。更多还原

【Abstract】 Chromium nitride （CrN） are widely used because they possess many excellent physical and chemical properties. Like the high wear resistance, antiferromagnetism which other transition metal don’t possess and the properties of decomposeing high activity nitrogen （N₂） when it’s heaten. Nevertheless, preparing CrN is very difficult because of the low activity of Cr, and because of its high brittleness, study of sintering samples is very little, either. Therefore, simplifying the preparation of CrN is an issue for the widely application of refractory compounds. The CrN_x powders fabricated by means of MA were sintered by SPS. The sintered samples possess excellent mechanical properties.The mixed powders of Cr₂N and Cr were mechanical alloyed to synthesize nonstoichiometric CrN_x. An X-ray diffractometer （XRD） and a sanning electron microscope （SEM） were used to analyze the structures and observe the morphologies of the milled powders. A differential scanning calorimetry （DSC） was used to analyze the structure of the mixed powders after being heaten up.The CrN_x powder fabricated by means of MA was sintered at different temperature under vacuum and at the pressure of 20 MPa. The fracture surfaces of the sintered samples were investigated by SEM and the mechanical properties were tested.The results of structure analyze of mixed powders showed that with the Cr content increased ,the grain size of CrN_x was increaseand at first then decreased and the change of N₂ content which was been decomposed after heaten was the same under the condition of same MA time. with the MA time increased ,the grain size of CrN_x was decreased gradually and the change of N₂ content which was been decomposed after being heaten up was decreased under the condition of same proportion of rough material. The result of SEM showed that with the Cr content increased ,the degree of aggregation of the MAed powders was increased ,and the granularity were increase at first, then decreased under the condition of same MA time; with the MA time increased , the granularity was decreased gradually then reach the balance finally under the condition of same proportion of raw material. The results of structure analyze and mechanical properties of the sintered samples showed that as sintering temperature increased, the grain size of the sintering samples was decreases, desity, microhardness, breaking strength were increased. The mechanical properties for the sintering sample of the Cr₂N and Cr powders mixed as 1:0.5 molar ratio milled for 50h are optimum. The desity, microhardness, and rupture strength are 22.09GPa, 99.5% and 239.1MPa.更多还原