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球形碳化钨增强金属基复合涂层具有高硬度、高韧性和优异的耐磨、耐蚀性等特点,可以对材料表面起到有效保护作用。传统铸造碳化钨粉体多呈不规则的片状或多角状,流动性差且硬度低,难以满足高性能涂层材料的要求。本文以多角状铸造碳化钨粉体为原料,采用感应等离子体技术制备球形碳化钨粉体,研究感应等离子体技术工艺参数对碳化钨粉体球化效果的影响规律。采用扫描电子显微镜、X射线衍射仪、霍尔流速计、激光粒度分析仪等对球化处理前后碳化钨粉体的形貌、物相、松装密度、粒度分布进行表征。结果表明:送粉率为110 g/min、载气流量为5.0 L/min时,采用感应等离子体技术可制备颗粒饱满、表面光滑、分散性良好,球化率高达99%以上,且球形度较好的球形碳化钨粉体。球化后碳化钨粉体无孔洞等缺陷,内部组织为典型的细针状WC和W2C的共晶,组织结构均匀细密。球化后碳化钨粉体的硬度高达3 258HV,提高了408HV;球化后碳化钨粉体的松装密度由8.01 g/cm3提高到9.75 g/cm3,霍尔流速由10.30 s/50 g降低到6.80 s/50 g,粉体的流动性提高。 相似文献
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为了使纳米氮化硅粉体能够均匀地分散在聚合物中并与聚合物具有良好的相容性,必须对其进行表面改性。本文中用BA-MMA-GMTS三元共聚物作为纳米Si3N4粉体表面改性剂,对纳米Si3N4粉体进行湿法包覆反应改性。结果表明:BA-MMA-GMTS三元共聚物包覆在纳米Si3N4粉体的表面,并与其发生了化学作用,有效地阻止了纳米Si3N4粉体的团聚,当BA-MMA-GMTS三元共聚物相对纳米Si3N4粉体质量比为10%时包覆效果最好。改性后的Si3N4粉体粒径明显减小,在有机溶剂中的分散性良好,由于相似相容原理,可以推测改性后的纳米Si3N4粉体必能与聚合物具有良好的相容性并且能更加均匀地分散在其中。 相似文献
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Si3N4陶瓷具有高硬度、高耐磨以及高抗弯强度等优异特性,常常被应用于冶金、化工以及航空航天等现代化领域.Si3 N4的强共价键使其难以致密化,因此热压烧结和气压烧结是目前制备致密Si3 N4陶瓷最常见的方法.然而极高的烧结温度以及较大的N2压力需求等极其苛刻的制备条件限制了致密Si3 N4陶瓷的基础探索研究和工业化生产应用.因此,本工作提出设计以传统空气电炉作为烧结装置,通过埋碳低温制备致密Si3 N4陶瓷,研究该工艺条件下实验用坩埚、填埋Si3 N4粉体以及烧结试样的物相变化和微观结构,结果表明:(1)Si3 N4的分解使得坩埚表层生成不规则的SiC纤维堆积,较低的氧分压使所埋Si3 N4粉体经烧结后仍存在较多Si3 N4和少量Si2 N2 O;(2)烧结后的试样仅表面存在少量Si2 N2 O,而试样内部并未出现Si2 N2 O相;(3)1650℃低温烧结后试样致密度达到98%以上,显微组织均匀,且具有良好的性能. 相似文献
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《纳米技术与精密工程》2016,(5)
本文将单质Ti粉、Si粉和C粉作为反应原料,利用机械合金化-热处理工艺制备高纯度的Ti_3SiC_2陶瓷粉体材料,研究了热处理温度对球磨粉体中Ti_3SiC_2纯度的影响.研究表明:单质混合粉体经过机械合金化可制备出含有TiC、TiSi_2等杂质相的Ti_3SiC_2陶瓷粉体,其中Ti_3SiC_2质量分数为71.5%;对球磨粉体进行热处理真空提纯发现,热处理温度对球磨粉体中的Ti_3SiC_2含量影响较为明显,当热处理温度为950℃时,粉体中Ti_3SiC_2质量分数提升至95%. 相似文献
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以纯Nb粉末、纯Si粉末或Nb_5Si_3粉末为原料,采用预置粉末法和双通道同轴送粉法,通过激光熔化沉积(LMD)技术制备3种Nb-16Si二元合金。使用SEM,EDS和XRD等手段分析合金的显微组织特征。结果表明:LMD制备的Nb-16Si合金均由NbSS和Nb_3Si两相组成。原料粉末的堆叠方式和化学状态强烈影响合金的显微组织。以纯元素粉末为原料,预置粉末法制备的Nb-16Si合金,由尺寸约1~5μm的枝晶状初生NbSS和NbSS/Nb_3Si共晶组织组成,合金显微硬度约773HV;双通道同轴送粉法促使显微组织细小均匀化,合金中初生NbSS相呈近等轴状均匀分布,平均尺寸仅约2μm,合金硬度提高至817HV;以Nb+Nb_5Si_3粉末为原料,双通道同轴送粉法制备的Nb-16Si合金呈伪共晶组织,其显微硬度高达907HV。 相似文献
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X.H. Wang K. Eguchi C. Iwamoto T. Yoshida 《Science and Technology of Advanced Materials》2013,14(4):313-317
With ultrafine SiC powder as starting material, thermal plasma physical vapor deposition has been applied successfully to the deposition of SiC films on Si substrates. The control of processing parameters such as substrate temperature, powder feeding rate and composition of plasma gases, permits the deposition of SiCfilms on a wide area of around 400 cm2 with a variety of microstructures fromamorphous to nanostructured and with various morphologies from dense to columnar. For the nanostructured case, the crystallite size was between 3 and 15 nm and the maximum deposition rate calculated based on the actual deposition duty time reached 200 nm/s. The deposition mechanism is discussed briefly. 相似文献
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X. H. Wang K. Eguchi C. Iwamoto T. Yoshida 《Science and Technology of Advanced Materials》2002,3(4):94
With ultrafine SiC powder as starting material, thermal plasma physical vapor deposition has been applied successfully to the deposition of SiC films on Si substrates. The control of processing parameters such as substrate temperature, powder feeding rate and composition of plasma gases, permits the deposition of SiC films on a wide area of around 400 cm2 with a variety of microstructures from amorphous to nanostructured and with various morphologies from dense to columnar. For the nanostructured case, the crystallite size was between 3 and 15 nm and the maximum deposition rate calculated based on the actual deposition duty time reached 200 nm/s. The deposition mechanism is discussed briefly. 相似文献
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Silicon oxide films have been deposited with remote plasma chemical vapour deposition (RPCVD) at low temperatures (<300 °C) from SiH4---N2O. The effect of a gas-phase reaction on the SiO2 film properties and Si/SiO2 interface was investigated. As the partial pressure ratio was increased above N2O/SiH4 = 4, a gas-phase reaction with powder formation was observed, which degraded film properties, increased surface roughness, and decreased deposition rate. When N2O/SiH4 <4, there was no detectable IR absorption in the film associated with hydrogen-related bonds (Si---OH and Si---H) but when N2O/SiH4 >4, the incorporation of Si---OH bond became significant and Si1+, intermediate state silicon at the interface, was more abundant. The oxide fixed charge, interface trap density, surface roughness and leakage current were increased when there was powder formation in the gas phase. High plasma power also favoured the powder formation in the gas phase. C---V and I---V characteristics were measured and it was shown that these electrical properties were directly related to the process condition and material properties of the oxide and the Si/SiO2 interface. 相似文献
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Ultra-fine silicon nitride powder was synthesized from the SiCl4-NH3-H2-Ar system using a d.c. plasma torch reactor (production rate 150–400 g h−1). The powder produced is pure white, fluffy and amorphous. The particles are spheroidal in shape with a mean diameter between
30–60 nm forming aggregates of 0.1–0.4 μm depending on the operational conditions. Chemical analysis on the crude powder handled
at ambient atmosphere revealed: N(−NH4Cl):37–39%, O:3–5% and Cl:2–3%. The amorphous powder can be crystallized around 1500 °C under nitrogen to give an α-phase
content in excess of 90%. Infrared spectra can be used to semi-quantitatively determine the NH4Cl content of the crude powder. That proportion is between 2.5 and 4%. The influence of some process parameters e.g. (N/Si
and H2/N molar ratios, internal pressure) on powder properties was also investigated. The N/Si molar ratio was found to be the most
important parameter for the powder composition whereas the internal pressure plays a major role on the powder morphology. 相似文献
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文中提供了带倾斜角振动171极的等离子体反应室及他用于刻蚀硅粉的实验结果。振动171极上硅粉的运动分析表明其在反应区滞留的时间可达数分钟之久,这就使低纯硅粉的纯化处理可一次完成。刻蚀速率模型几个关键公式的计算结果表明中性高能粒子的刻蚀效果不可忽视。理论分析与实验数据大致吻合,这证明新的反应室用于粉粒表面刻蚀和纯化都大大优于立式反应室。 相似文献
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以Cr-Si-Ni合金粉末为原料、利用激光熔敷技术在A3低碳钢表面上制得了以金属硅化物Cr3Si为增强相,以Cr2Ni3Si复杂金属硅化物为基体的快速凝固Cr3Si/Cr2Ni3Si复合材料冶金涂层,分析了该涂层的显微组织,并分别在干滑动磨损及二体磨料磨损条件下测试了该涂层的耐磨性能。研究结果表明,由于激光熔敷Cr3Si/Cr2Ni3Si快速凝固复合材料涂层组织细小、均匀,在滑动磨损过程中不易与对偶件粘着、在磨料磨损过程中具有很高的抗切削抗剥落能力,因而在干滑动磨损及二体磨料磨损条件下涂层均具有优良的耐磨性能。 相似文献
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采用双反应室激光气相合成纳米粉体装置,以六甲基二硅胺烷((Me3Si)2NH)(Me:CH3)为原料合成了纳米Si/C/N复相粉体,粒径为20 nm~30 nm。研究了纳米Si/C/N复相粉体在8.2 GHz~18 GHz的微波吸收特性,结果表明:纳米Si/C/N复相粉体介电常数的实部(ε')和虚部(ε″)在8.2 GHz~18 GHz随频率增大而减小,介电损耗(tgδ=ε″/ε ')较高,是较为理想的微波吸收材料;纳米Si/C/N复相粉体在不同基体中的微波吸收特性出现很大差异。纳米Si/C/N复相粉体中的SiC微晶固溶了大量的N原子,形成大量带电缺陷,极化弛豫是吸收微波的主要原因。根据纳米Si/C/N复相粉体与石蜡复合体的实测介电参数,设计出多组在8 GHz~18 GHz范围内微波反射系数R≤-8dB的吸波涂层结构。 相似文献