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硬质合金注射成形脱脂工艺与碳含量控制 总被引:1,自引:0,他引:1
将传统蜡基粘结剂和油+蜡改进粘结剂体系分别与粒度为1.97μm的WC-8Co硬质合金粉末混合采用注射成形法制备了全致密高强度的硬质合金。研究了注射坯在Hz中的热脱脂工艺和溶剂脱脂与其后补充热脱脂工艺,和不同脱脂工艺对脱脂坯碳含量的影响。结果表明:油+蜡改进粘结剂体系具有更好的热脱脂和溶剂脱脂行为。通过工艺优化和碳含量控制,在真空气氛下1400℃烧结80min制备出高抗弯强度的全致密硬质合金烧结制品。 相似文献
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注射成形Kovar合金脱脂工艺的研究 总被引:1,自引:0,他引:1
采用蜡基多聚物为粘结剂体系,研究了注射成形Kovar合金的脱脂工艺.以喂料的热分析结果为指导,制定出合理的热脱脂工艺,对于6 mm× 6 mm× 50 mm的注射坯,总共热脱脂时间约为18 h.采用三氯乙烯为有机溶剂,研究了注射坯的溶剂脱脂工艺,在脱脂温度为40℃,溶剂脱脂6 h后,粘结剂的脱除率可达54%.利用注射成形工艺可以制备出热膨胀系数为(4.5~6.0)×10-6K-1(25~450℃),气密性小于1.2×10-9Pa·m3·s-1的封装盒体. 相似文献
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《硬质合金》2014,(6):340-346
研究了超细硬质合金WC-6%Co注射坯的溶剂脱脂-热脱脂工艺,讨论了脱脂时间、脱脂温度、注射坯形状和固液比等工艺参数对溶剂脱脂速率的影响,通过改善溶剂脱脂-热脱脂工艺,得到了高性能超细硬质合金台阶状圆棒。结果表明:溶剂脱脂速率随着脱脂温度的升高而上升,随时间的延长而降低;溶剂脱脂3 h后,台阶状圆棒中可溶粘结剂基本脱除。溶剂脱脂时,弓形棒和台阶状圆棒的平均脱除速度较快,圆台棒的平均脱除速率较慢,即溶剂脱脂速率与注射坯的S/V(表面积/体积)值成正比。固液比越小,粘结剂平均脱除速率越高;在稳定阶段,残留可溶粘结剂量高的注射坯脱脂速率快。溶剂脱脂时,粘结剂从外向内脱除,内部可溶粘结剂在形成脱除通道后快速脱除。经过DSC分析,溶剂脱脂坯中存在少量高聚物共混物,需改善热脱脂工艺。优化脱脂工艺后,超细WC-6%Co硬质合金台阶状圆棒的碳含量合适,WC晶粒度为0.35μm,硬度HV10为1 828,致密度大于99%,尺寸精度高。 相似文献
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粉末注射成形溶剂脱脂过程的数学模型 总被引:3,自引:0,他引:3
从宏观的角度出发 ,仅考虑脱脂预成形坯的体积、粘结剂含量对脱脂过程的影响 ,将预成形坯几何形状等其他因素的影响合理地归结到扩散系数函数中。根据浓度扩散原理建立了描述粉末注射成形溶剂脱脂过程中预成形坯粘结剂含量随时间变化的数学模型 ,避免了求解用Fick第二定律描述的偏微分方程 ,得出了一种预测脱脂量与脱脂时间的有效方法。根据模型求出了脱脂速度函数 ,给出了一种控制溶剂脱脂过程产生缺陷的分段升温优化方法。用该模型对硬质合金注射成形溶剂脱脂过程进行了模拟和预测 ,预测结果与实验结果吻合较好 相似文献
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M.A. Omar R. Ibrahim M.I. Sidik M. Mustapha M. Mohamad 《Journal of Materials Processing Technology》2003,140(1-3):397-400
Wax-based binder system is widely used but they suffer from long debinding time and a tendency to slump or distort during debinding. This has been a major obstacle for the economic process for metal injection moulding (MIM). For improving the debinding process, two-step debinding process has been introduced. Gas-atomised 316L stainless steel powder was injection moulded using two types of multi-component binder system comprising (1) a major fraction of paraffin wax and a minor fraction of polyethylene (PE) and stearic acid (SA) as a lubricant, (2) a major fraction of polyethylene glycol (PEG) and a minor fraction of polymethyl methacrylate (PMMA) binder system. Debinding was carried out in two steps; first, the moulded part is immersed in heptane or distilled water at 60 °C to remove the major component of the binder and then heated to remove the remaining binder. The results show that no swelling or distortion was observed on the moulded specimens on both binder systems. Furthermore, the specimens had an adequate strength for handling even after solvent extraction. Large pore were formed from the surface to the interior of the debound part during solvent extraction, allowed easy escape of pyrolysis gases during thermal debinding. Thermal debinding with ramp heating at rates from 3 to 15 °C/min was found to be successful. 相似文献
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MIM零件连续烧结设备及其控制技术 总被引:2,自引:0,他引:2
通过对MIM成形工艺过程的分析,根据粉末注射成形零件的特点,论述了应将传统脱脂、烧结乃至后处理等单一工序融合为综合工序的必要性,并提出了连续烧结设备的结构与控制模式。 相似文献
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1 INTRODUCTIONMetalpowderinjectionmolding (MIM )isane mergingadvancednet shapingtechnology ,whichof fersimportantadvantagesovertheconventionalpow dermetallurgy .Thistechnologyhasattractedmoreandmoreattentionandundergonerapiddevelopmentintherecentyears[1~ 4 ] .… 相似文献
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Li Songlin 《中国有色金属学会会刊》1999,9(3):2
1 INTRODUCTIONRecentlymanydebindingtechniqueshavebeenstudiedinmetalpowderinjectionmolding(MIM),includingthermaldebinding,capillarydebinding,catalyzeddebindingetc[1~5].Comparedwithotherdebindingtechniques,thesolventdebindinghastheadvantagesoflittled… 相似文献
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Hardmetal and cermet bodies were printed by fused-filament fabrication (FFF) and composite-extrusion modelling (CEM) in an SDS (shaping – debinding – sintering) process. For FFF the filaments were prepared from hardmetal (WC-10Co) and cermet powder (Ti(C,N)-Co/Ni-based) and organic binder. The CEM feedstock consisted of WC-Co MIM powder. A 3D filament printer as well as a 3D printer working with a MIM granulate were employed to fabricate printed bodies by FFF and CEM, respectively. The solvent debinding process was performed in cyclohexane (FFF-printed bodies) or water (CEM-printed bodies). Thermal debinding of all parts was performed in a tube furnace up to a temperature of 800 °C. The pre-sintered parts were then subjected to vacuum sintering by application of conventional vacuum sintering profiles up to 1430 °C for hardmetals and up to 1480 °C for cermets. Dimensional and mass changes upon the various preparation steps as well as microstructure and porosity of the sintered bodies were investigated. While the microstructure is practically identical to that of conventionally prepared materials, some cavities were present from the printing process because of yet non-optimised printing strategy. By change of printing strategy the cavities could be minimised or even avoided. The study shows that with the applied 3D extrusion-printing techniques, hardmetal and cermet components with innovative geometries are accessible. 相似文献
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金属注射成形技术进展 总被引:12,自引:0,他引:12
分析了影响金属注射成形(MIM)产业化进程的两个主要技术因素,即适合MIM要求的原料粉末的生产方法和MIM生产工艺,并概述了目前MIM技术的发展状况。 相似文献
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硬质合金注射成形脱脂过程中的碳含量控制 总被引:4,自引:0,他引:4
研究了不同脱脂气氛 (不同比例N2 与H2 的混合气体 )和脱脂方法 (热脱脂、溶剂脱脂 热脱脂、冷凝蒸汽脱脂 热脱脂 )对PIM硬质合金脱脂坯及合金碳含量的影响。结果表明 :N2 热脱脂粘结剂容易以炭黑的形式残留在脱脂坯中 ,造成合金增碳 ;H2 热脱脂导致合金脱碳 ;75 %N2 2 5 %H2 (体积分数 )混合气体热脱脂既能有效地脱除粘结剂 ,又能保证合金碳含量相对稳定 ;溶剂脱脂和冷凝溶剂脱脂能显著缩短脱脂时间 ,而且由于高温保持时间短 ,在后续热脱脂过程中采用H2 作保护气也可获得满意的碳含量 ,说明该方法对工艺条件的适应性强。通过调整热脱脂高温保持时间 ,可在一定范围内对脱脂坯的碳含量进行调整 ,说明过程的可调控性好。与溶剂脱脂相比 ,冷凝蒸气脱脂粘结剂脱除率更高 ,脱脂坯有较高的强度 ,有效地防止了脱脂坯软化变形的现象。 相似文献
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大厚度钨基合金正挤压棒坯的溶剂脱脂特性 总被引:1,自引:1,他引:0
为了实现厚度达15 mm钨基合金正挤压棒坯的无缺陷脱脂,对大厚度正挤压棒坯的溶剂脱脂行为和机理以及大厚度棒坯溶剂脱脂过程的优化方法和效果进行研究。结果表明:大厚度棒坯的溶剂脱脂对温度非常敏感,极易产生脱脂缺陷;棒坯厚度增大,粘结剂脱除速率降低,产生缺陷的几率增大,d 12 mm和d 15 mm棒坯的适宜溶剂脱脂工艺为(30℃,12 h);d 15 mm棒坯在30℃下脱脂6 h,脱脂量不足30%,且随着脱脂时间的进一步延长,脱脂速率显著下降;大厚度棒坯的溶剂脱脂受扩散控制,棒坯越厚,扩散路径越长,棒坯脱脂速率越小;采用短周期多次浸溶剂方法来优化脱脂过程,实现了正挤压棒坯的无缺陷脱脂,且d 12 mm和d 15 mm棒坯的脱脂量分别可高达55%和45%以上。 相似文献
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以93W-Ni-Fe粉末挤压成形坯为研究对象,在研究溶剂脱脂动力学的基础上,考察溶剂种类、溶剂加入方式以及脱脂温度对溶剂脱脂过程的影响,并对脱脂前后的坯体断口进行SEM观察。结果表明:以正庚烷作为脱脂溶剂,具有较高的脱脂率,脱脂坯无鼓泡、开裂等缺陷;通过分段优化的脱脂工艺,在45℃的正庚烷中脱脂8 h,脱脂过程中周期性更换溶剂,最终可脱除65%以上的石蜡,且整个脱脂过程均为扩散控制,相应的动力学参数为1.6751×10-5 cm2/s。 相似文献
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钛及钛合金粉末的注射成形 总被引:2,自引:1,他引:2
介绍了钛及钛合金粉末注射成形技术的发展、应用现状及制备工艺。指出了钛及钛合金粉末注射成形技术研究方向和扩大应用的途径是:①使用价格低廉的氢化脱氢粉和气体雾化粉混合得到的钛及钛合金粉作为注射成形的原料粉末;②开发新型高效的钛及钛合金粉末注射成形用的粘结剂体系;③优化混炼工艺;④优化注射条件参数以消除注射缺陷;⑤开发先进的脱脂工艺,使脱脂时间进一步缩短并减少脱脂缺陷,以降低成本;⑥研究钛及钛合金烧结工艺以及超小型零件的注射成形工艺,控制产品尺寸精度,提高产品性能。扩大产品的尺寸。 相似文献