共查询到18条相似文献,搜索用时 140 毫秒
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采用溶剂沉淀法制备了用于3D打印的尼龙(PA)6/PA12复合粉末,使用扫描电子显微镜和X射线衍射对复合粉末微观形貌与结构进行分析,使用差示扫描量热测试了复合粉末的熔融和结晶温度,同时测试了不同PA12含量下复合粉末的表观密度、粒径分布、熔体流动速率(MFR)和注射成型件的力学性能。结果表明,复合粉末颗粒近球形,其结晶度明显低于纯PA6粉末的结晶度,当PA12的质量分数增加至20%时,复合粉末的结晶度由纯PA6的66.48%降至42.66%;随着PA12含量的增加,复合粉末的表观密度减小,粒径大于150μm的粉末含量增加,当PA12质量分数为20%时,复合粉末的表观密度仍大于0.35g/cm~3,粒径在75~100μm的粉末含量虽有所减少,但仍在70%以上,且加入成核剂可明显减少大粒径粉末的含量;MFR及注射成型件的韧性随PA12含量增加而提高,但成型件强度和模量下降;PA12使复合粉末的烧结温度有明显的降低,烧结温度窗口增大,有利于选择性激光烧结。 相似文献
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《塑料工业》2017,(8)
通过机械混合法制备了聚苯乙烯(PS)/丙烯腈-丁二烯-苯乙烯三元共聚物(ABS)的复合粉末。针对选择性激光烧结成型件精度不高的问题,在预热温度75℃、激光功率25 W的条件下,研究了扫描间距、扫描速度和单层厚度对PS/ABS成型件长(X)、宽(Y)、高(Z)三个方向尺寸精度的影响,并用正交试验对工艺参数进行优化。结果表明,PS/ABS复合粉末烧结时,成型件的Z向尺寸相对误差变化最大;在所研究的工艺参数中,扫描速度对成型件尺寸精度影响最大,单层厚度影响最小;确定最优的工艺参数组合为扫描间距0.32 mm、扫描速度1 800 mm/s和单层厚度0.28 mm,此时Z向尺寸相对误差为0.32%。 相似文献
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《塑料工业》2018,(11)
为了解决聚苯乙烯(PS)选区激光烧结(SLS)成型件质量较差的问题,使用不同工艺下的芳纶纤维(AF)作为增强改性材料制备了两种PS/AF复合粉末材料;在激光功率30 W,轮廓扫描速度2 200 mm/s等条件下,通过控制变量法分别研究了预热温度、分层厚度及填充扫描速度对两种PS/AF复合粉末材料SLS成型件精度及弯曲强度的影响规律。结果表明,PS/AF复合粉末材料SLS成型件的X、Y向尺寸精度不受工艺参数变化的影响;以聚合球磨AF为填料的PS/AF复合粉末材料成型件整体上的Z向成型精度较好,但其弯曲强度值低于以短切AF为填料的PS/AF复合粉末材料;在试验范围内,得到预热温度、分层厚度及填充扫描速度较优工艺参数范围为85~95℃,0. 20~0. 24 mm和1 400~1 800 mm/s。 相似文献
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针对聚苯乙烯(PS)粉末选择性激光烧结(SLS)成型件强度较低的问题,采用机械混合法制备了PS/苯乙烯–丁二烯–苯乙烯嵌段共聚物(SBS)/纳米CaCO3复合粉末,通过单因素实验分析了SLS工艺参数对成型件弯曲强度的影响,并通过正交试验和极差分析获得了最优工艺参数组合。实验结果表明,烧结件的弯曲强度随着激光功率的增大而升高,随着扫描速度、扫描间距和分层厚度的增大而降低;激光功率对PS/SBS/纳米CaCO3复合粉末烧结件弯曲强度的影响最大,分层厚度对弯曲强度的影响最小,扫描速度和扫描间距的影响介于两者之间;最佳工艺参数组合为:激光功率27 W,扫描速度1300 mm/s,扫描间距0.24 mm,单层厚度0.22 mm。在此工艺参数组合下PS/SBS/纳米CaCO3复合粉末烧结件的弯曲强度为13.38 MPa;改性纳米CaCO3与PS和SBS的相容性较好,能有效起到增强的作用。 相似文献
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利用十八烷基三甲基溴化铵(OTAB)对蒙脱土(MMT)进行有机改性,并通过溶液插层法制备尼龙12/有机蒙脱土(PA12/OMMT)纳米复合粉末。利用X射线衍射、傅立叶变换红外光谱、扫描电子显微镜等手段对改性后的MMT及PA12/OMMT纳米复合粉末的结构和微观形貌进行表征,并将复合粉末热压成型制成标准件,测试其力学性能和热性能。结果表明,经过有机改性,MMT的层间距由1.24 nm增加到了2.13 nm,且改性后的MMT能均匀地分散在PA12基体中,PA12/OMMT纳米复合粉末的成型件在拉伸强度、弯曲强度、冲击强度和热性能方面都优于纯PA12粉末。PA12/OMMT纳米复合粉末为选择性激光烧结技术(SLS)提供了一种性能良好的粉末材料。 相似文献
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《Journal of the European Ceramic Society》2007,27(2-3):979-985
In order to reveal the fundamentals of the field assisted sintering technique (FAST), also known as spark plasma sintering (SPS), the evolution of the current density and temperature distribution in the punch-die-sample set-up during FAST of ZrO2–TiN powder mixtures was modeled by finite element calculations supported by in situ measured electrical and thermal input data. The thermal and electrical properties of partially sintered composite powder compacts were estimated using theoretical mixture rules, allowing to calculate the current density and temperature distribution inside the tool and the specimen during the FAST sintering process. The electrical properties of the sintering composite powder compact, and hence the thermal distribution in the sinter set-up, changed drastically during densification once percolation occurred. Based on the calculated thermal distribution inside the composite powder compact, an optimal tool-powder compact design was determined in order to process electrically conductive ZrO2–TiN composites from electrical insulating powder compacts within minutes with high reproducibility. 相似文献
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利用热空气处理法和浓硝酸处理法分别对碳纤维(CF)进行表面处理,然后与尼龙(PA)12粉末按量比3∶7通过机械混合法制备PA12/CF复合粉末材料。将复合粉末材料进行注塑成型,考察了热处理温度及浓硝酸处理时间对复合材料力学性能和热性能的影响。结果表明,浓硝酸处理时间为1 h处理效果最好,与未处理的CF复合材料相比,注塑样条拉伸强度提高23%,弯曲弹性模量提高133%,维卡软化点提高6.2℃;扫描电子显微镜分析表明,经过热处理后的CF在PA12基体中分散均匀,两者的界面相容性良好。 相似文献
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利用硅烷偶联剂KH560对滑石粉进行表面改性,之后将其与聚苯乙烯(PS)粉机械共混,制备PS/改性滑石粉复合粉末。在预热温度85℃和8层网格支撑等条件下,采用选择性激光烧结(SLS)工艺将粉末制备成烧结件。采用扫描电子显微镜观察了滑石粉与PS的界面,发现通过对滑石粉进行表面改性,不仅可以使其均匀地分散于PS粉中,而且两者的相容性也得到了改善。通过正交实验法研究了SLS工艺参数对PS/改性滑石粉烧结件力学性能的影响。利用极差分析法与综合平衡法得到了多指标下的最优工艺参数组合,即单层厚度0.18 mm,扫描间距0.28 mm,激光功率27 W,扫描速度1 200 mm/s,此时PS/改性滑石粉烧结件的拉伸强度为4.29 MPa,弯曲强度为14.4 MPa,冲击强度为4.4 k J/m~2,相比纯PS粉烧结件分别提高了4.9%,10%和56%。 相似文献
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Geng-fu Xu Tayo Olorunyolemi Yuval Carmel Isabel K. Lloyd Otto C. Wilson 《Journal of the American Ceramic Society》2003,86(12):2082-2086
A multilayer insulation configuration suitable for microwave sintering of ceramics up to 2100°C was designed and tested successfully. The configuration is based on porous, granular BN/ZrO2 fiber composite powder for packed beds and spacer cylinders. This insulation allows stable, controlled microwave sintering and can be modified to microwave process materials with different thermal, dielectric properties with improved properties. 相似文献
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《Ceramics International》2023,49(16):26747-26758
WC-Si3N4 composite structural material with excellent mechanical properties is essential for achieving high-strength connections between WC and Si3N4. Proper powder mixing process can significantly improve the mechanical properties of sintered samples. This study investigates the effects of two different ball milling methods: (1) mixing WC powder, Si3N4 powder, and sintering aid powders and then ball milling for 24 h (BM24); and (2) ball milling WC powder, Si3N4 powder, and sintering aid powders separately for 12 h and then ball milling in same jar for 12 h (BM12 + 12), as well as WC content on sintering shrinkage behavior of mixed powders. Furthermore, the bonding between the layers of one-time sintered sample of the WC-Si3N4 composite structure was investigated. The results showed that the microstrains of powders prepared by BM24 mixing process were greater than those of the powders prepared by BM12 + 12 mixing process. Shrinkage displacements and shrinkage rates during sintering of BM12 + 12 powders were greater than those of BM24 powders to varying degrees. Moreover, sintering temperature at which shrinkage rate of composite powders reaches its maximum value gradually increases as WC content decreases, while maximum value of shrinkage rate gradually decreases. Additionally, mechanical properties of all BM12 + 12 samples were better than those of BM24 samples. WC-Si3N4 composite structure sample sintered with BM12 + 12 powders had a smooth transition between the layers without any defects. 相似文献
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针对表面涂层技术工艺复杂,容易剥落等问题,提出了预渗入法制备陶瓷涂层技术。即预先将坯体造孔,再用纳米陶瓷粉与合金粉通过特殊方式合成制成复合粉,将该复合粉涂于有孔坯体的表面,使粉料进入孔洞中;在气氛保护条件下烧结,使复合粉与基体材料同时烧结并形成冶金结合界面,有效提高了表面性能。利用扫描电镜观察了衬瓷层的显微组织,分析了纳米氧化锆陶瓷成分在衬瓷层中的分布规律;发现ZrO2含量为20%-40%时均可得到较为理想的衬瓷层;氧化锆陶瓷相从表面向基体呈递减趋势;决定衬瓷层的厚度的最重要原因是直孔洞的深度。 相似文献