【作者】 张小锋；

【导师】 刘维良；

【作者基本信息】 景德镇陶瓷学院 ， 材料学， 2012， 硕士

【摘要】 通过使用国内不同型号的大气等离子体喷涂设备，采用等离子体球化技术对普通商业钨粉进行球化，球化过程中利用水冷系统收集钨粉，研究了等离子球化功率等因素对钨粉性能的影响,最终把球化后钨粉制备钨涂层。研究结果表明采用SULZERMetco-7MC喷涂设备球化的钨粉综合性能最佳，等离子球化普通钨粉所制得的钨粉具有球形度较高、流动性能较好、氧含量增加不大等特点。当球化功率为25kW时，球形钨粉的流动速度为5.9s/50g，氧含量为0.095wt%。以球化钨粉经还原处理后为原料，所制备出的涂层与普通钨粉相比性能有了较大的提高。此外加入不同的梯度过渡层可制备出性能较好的钨涂层，与不加入过渡层相比，涂层在致密度、热导率、结合强度等性能有了较大的提高。采用冷动力喷涂法以钨和钨-镍-铁合金为原料在铜合金基体上制备了钨涂层和钨镍铁合金涂层。其中研究了冷喷涂过程中钨粉粒径、喷涂距离等因素对涂层性能的影响。用扫描电子显微镜等手段分析了涂层的表面、断面微观结构，并用原子力显微镜测量了涂层的粗糙度。此外，本文计算了冷喷涂过程中粉末颗粒的实际速度，并采用有限元分析软件ANSYS/LS-DYNA模拟了冷喷涂过程中颗粒撞击基体时的变形情况。当采用D50分别为2、7μm，喷涂距离为10～15mm时可在基体上制备出厚度为2μm的均匀、致密、结合强度较高的钨涂层，无明显氧化。当采用粉末粒径D50分别为2、7μm的W-Ni-Fe合金，可在基体上制备出厚度达80μm的均匀、致密、结合强度较高的涂层，涂层无明显氧化。根据模拟计算钨的临界速度为580m/s,钨颗粒在喷涂过程中速度为722.1～794.8m/s。采用金属有机化学气相沉积（MOCVD）的方法以羰基钨为前驱体在CuCrZr合金和低活化钢上制备了钨涂层，并且在实验过程中对沉积设备进行了改造。当沉积温度在270～600℃，羰基钨升华温度在90℃左右，最终在CuCrZr合金和低活化钢上制备了β-W。经实验证实沉积温度是影响钨涂层最终性能最重要的一个因素，当沉积温度为500℃时能制备出性能较优的涂层，经一定温度700～800℃条件下进行退火，涂层由β-W向a-W转变，即由介稳状态相转变为稳定相。此外，以CuCrZr合金为基体制备的涂层比低活化钢上制备的钨涂层在厚度、结合性能等方面较优。更多还原

【Abstract】 Ordinary tungsten powder was spheroidized by different types of atmosphere plasma spraying machine with water cooling system. The influence of power to properties of tungsten powder was studied. The results indicate that the tungsten powder has a high degree of spherical. When the power is low, the tungsten powder has high recycle rate, low oxygen content, high flowability; however, when the power is high, the tungsten powder has a low recycle rate, high oxygen content, poor flowability. Under the same process conditions, the powder by different atmosphere plasma spraying machine have different characteristics. Furthermore, the device of SULZER Metco-7MC has good performances to prepare spherical tungsten powder. When tungsten was spheroidied by7MC at25KW, its flowability is5.9s/50g, oxygen content is0.095/wt%. The tungsten coating with spherical powders has higher density, bond strength, etc than using normal powders. Besiedes, different graded interlayers are used in coating, compared the coating without graded interlayers, the form coating have high bond strength and density, etc.Results of optical microscopy, scanning electron microscopy, AFM are presented for tungsten and W-Ni-Fe coating produced by low and high cold gas dynamic spraying, respectively. With size D502and7μm, spraying distance10～15mm, high properties coatings without obvious oxide can be compared. The critical velocity of tungsten powder was calculated, what is more, tungsten particles collision was also simulated by soft ANSYS/LS-DYNA. Cold gas dynamic spray (CGDS) is a rapidly developing coating technology, in which spraying particle is deposited through plastic impact on s substrate at high velocities at low temperature. In these experiments, the process produced a reasonably dense tungsten coating and tungsten alloy coating. This paper reports the effect of deposition parameters which including temperature, spraying distance, particle size, etc. on the structures formed.The tungsten membranes with ultra microstructure on CuCrZr alloy and CLAM substrates have been prepared using remaked cold-wall reactor, metal organic chemical vapor deposition (MOCVD). The membranes were produced by pyrolysing the tungsten hexacarbonyl in low pressure, at air and argon atmosphere. When formed at or below600℃, they were poorly crystalline. Besides, the membranes had low properties including thickness, density, bonding performance with substrate and so on. While above this temperature, the properties of tungsten membranes had been greatly improved, and all the membranes consist of tungsten in the β-W. Then annealed at700～800℃, β-W will be converted into a-W. As in other variations of the pyrolysis, oxygen is observed, although these reduce with increasing temperature of deposition. In addition, when filled with argon, the oxygen content will also reduce. Moreover, these membranes have stable chemical composition and microstructure. The bonding properties and polish of surface could be enhanced greatly. The coating on CuCrZr alloy has better properties than CLAM.更多还原