反应爆炸喷涂制备TiC／Fe-Ni金属陶瓷复合涂层

以钛铁粉、羰基镍粉和碳的前驱体(蔗糖)为原料,通过前驱体碳化复合技术制备Ti-Fe-Ni-C系反应热喷涂粉末,并通过爆炸喷涂技术原位合成并沉积TiC/Fe-Ni金属陶瓷复合涂层;利用XRD、SEM和EDS研究喷涂复合粉末和涂层的相组成、显微结构.结果表明:采用前驱体碳化复合技术制备的Ti-Fe-Ni-C反应喷涂复合粉末粒度均匀;所制备的TiC/Fe-Ni复合涂层由不同含量TiC颗粒分布于金属基体内部而形成的复合片层叠加而成,基体主要是(Fe,Ni)固溶体;TiC颗粒大致呈球形,粒度为纳米级;复合涂层的平均显微硬度HV0.2为18.9 GPa.     

Microstructure of reactive synthesis TiC/Cr18Ni8 stainless steel bonded carbides

TiC/Cr18Ni8 steel bonded carbides were synthesized by vacuum sintering with mixed powders of iron, ferrotitanium, ferrochromium, colloidal graphite and nickel as raw materials. The microstructure and microhardness of the steel bonded carbides were analyzed by scanning electron microscope (SEM),X-ray diffraction (XRD) and Rockwell hardometer. Results show that the phases of steel bonded carbides mainly consist of TiC and Fe-Cr-Ni solid solution. The synthesized TiC particles are fine. Most of them are not more than 1 μm With the increase of sintering temperature, the porosity of TiC/Cr18Ni8 steel bonded carbides decreases and the density and hardness increase, but the size of TiC panicles slightly increases. Under the same sintering conditions, the density and hardness of steel bonded carbides with C/Ti atomic ratio 0.9 are higher than those with C/Ti atomic ratio 1.0.The TiC particles with C/Ti atomic ratio 0.9 are much finer and more homogeneous.     

不同喷枪配置制备TiC/NiCrMo涂层组织结构及性能

采用SG-100型等离子喷涂喷枪,使用亚音速(Subsonic)和马赫一(Mach I)两种不同喷枪配置,在Q235钢表面制备了TiC/NicrMo涂层.用扫描电镜、X射线衍射仪和电子探针等分别对这两种涂层表面、截面形貌、相成分以及元素分布进行了分析.同时对两种涂层孔隙率、显微硬度及耐磨损性能进行了对比.结果表明,Mach I喷枪制备的涂层比Subsonic喷枪制备的涂层致密,孔隙率较小,涂层与基体结合良好,滑动磨损性能优于Subsonic涂层,显微硬度略高于Subsonic涂层;Subsonic喷枪制备的涂层与基体结合界面有分离现象出现,涂层中有较大空隙存在.两种涂层中TiC均发生氧化,生成TiO2;TiC与Mo也发生反应生成Mo2C.     

Synthesis of TiC–Al2O3 nanocomposite powder from impure Ti chips, Al and carbon black by mechanical alloying

The possibility of providing TiC–Al₂O₃ nanocomposite as a useful composite from low-cost raw materials has been investigated. Impure Ti chips were placed in a high energy ball mill with carbon black and aluminum powder and sampled after different times. XRD analysis showed that TiC has been synthesized after 10 h of milling. It could be observed from the width of XRD patterns’ peaks that the size of produced TiC crystallites is in the order of nanometer. In order to forming of TiC–Al₂O₃ composite, heat treatment was performed in different temperatures. Investigations have revealed that formation temperature of TiC as the dominant phase decreased for the milled specimens during heat treatment, also nanocrystalline TiC–Al₂O₃ composite was formed in this situation. Furthermore milling led to increase of strain and decrease of TiC lattice parameter while during heat treatment nanocrystalline grains grow up and strain decreases.     

激光熔化沉积(TiB+TiC)/TA15原位钛基复合材料的显微组织与力学性能

利用激光熔化沉积工艺制备了TiB+TiC增强相体积分数分别为9%、11%、22%及57%的4种(TiB+TiC)/TA15原位钛基复合材料。随增强相含量提高,TiB形态由片层状向棱柱状转化,TiC形态由不规则颗粒状向枝晶状转化,钛基复合材料硬度及弹性模量均显著提高而塑性明显下降。增强相体积分数约为9%的复合材料表现出较好的综合力学性能,增强相体积分数大于11%后复合材料的抗拉强度急剧降低。与激光熔化沉积态TA15钛合金相比,TiB+TiC增强相体积分数约为9%的复合材料抗拉强度（1040 MPa）及屈服强度（935 MPa）均提高约12%。      

TiC含量对钨基材料性能的影响

用热压烧结法制备了TiC含量 (体积分数 )分别为 0、10 %、2 0 %、30 %和 40 %的五种钨基材料 (TiC/W )。材料的硬度及弹性模量随TiC含量的增加而增大 ,分别由W基体的 3 4GPa、313GPa ,提高到 40 %TiC/W的 11 2GPa和 392GPa。随TiC含量的增加 ,材料的室温横向断裂强度和断裂韧度呈上升趋势 ,均在 2 0 %TiC/W时达到峰值 ,分别为 845MPa和 10 1MPa·m1/ 2 。随TiC含量增加 ,材料的热膨胀系数和比热容都增加 ,而热扩散率和热导率则显著下降。材料的热扩散率和热导率分别由W基体的 0 6 2 9× 10 -4 m2 /s和 15 3W / (m·K) ,提高到 40 %TiC/W的 0 110× 10 -4 m2 /s和 2 7 9W/ (m·K)     

固态反应法合成TiC

采用X射线、电子探针、DTA等方法,研究了Ti和C粉在机械合金化过程中的结构转变、晶粒度、颗粒度、形态、组织特征及微观结构变化规律。结果表明,通过自蔓延的模式在2小时左右可以生成纳米晶体TiC,TiC的晶粒度随球磨时间的延长变小,10小时可达7nm。晶格常数开始稍微变大,随后变小。     

超声振动对激光熔覆TiC/FeAl复合涂层温度场的影响

采用超声振动热效应转化和施加动态边界条件的方法对超声振动边界条件作近似处理,研究了超声振动辅助激光熔覆TiC/FeAl复合涂层的温度场分布规律,探讨了超声振幅和扫描速度对温度场的影响。结果表明,超声振动作用下,温度梯度为零的范围更大,温度场分布更为均匀;超声振动有效降低了涂层中和界面结合区的温度梯度及残余应力;超声振幅越大,扫描速度越小,基材和涂层的温度越高,涂层至界面结合区之间的温度梯度越小。     

灰铸铁表面原位合成TiC复合强化层的摩擦磨损性能

通过等离子束表面合金化工艺用Ti-Fe合金粉末在灰铸铁表面制备了原位合成TiC复合强化层。结果表明,合金化层厚度为350~400 mm,与基体之间实现良好的冶金结合。显微硬度测试结果显示,合金化处理后的试样表层硬度最高可达969 HV0.2。合金化区显微组织为残留奥氏体、针状马氏体和共晶莱氏体。XRD及SEM分析观察发现,在合金化区存在原位复合TiC颗粒。通过销-盘型高温摩擦磨损试验对合金化试样和未经合金化处理的灰铸铁试样的室温及高温（473 K、673 K）下的摩擦磨损行为及机理进行了对比研究,磨损试验结果表明,合金化处理后,试样的耐磨性能相对于灰铸铁基体得到了明显的改善,磨损率普遍下降3个数量级。根据扫描电镜（SEM）观察、能谱（EDS）检测和显微硬度测试的分析结果可知,基体表层金相组织转变和TiC颗粒是TiC复合强化层耐磨性能提高的主要原因。     

(Ti,Fe)-Al-C体系钢铁基复合材料的热力学计算与分析

利用溶液热力学理论,研究了(Ti,Fe)AlC体系钢铁基复合材料可能的反应产物的吉布斯自由能变化。热力学实验模型是在FeC熔液中加入钛铁合金(Ti,Fe)和纯铝块,继续加热到1600℃,熔液经过充分混合、反应后随炉冷却到常温。计算结果表明,TiC先于Fe2Ti、Fe3C等相生成,但始终没有Al4C3和TiAl3相产生;体系中TiC的热力学稳定性最高;在凝固过程中,TiC相优先析出,随后可能有Fe2Ti、Fe3C等相析出;铝含量的增加能够促进TiC、Fe2Ti、Fe3C等相的生成。