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为提高硅基陶瓷型芯的综合性能,将不同含量的氧化锆短纤维添加至以锆英粉为矿化剂的型芯基体粉料中,通过热压注法制备氧化硅陶瓷型芯,研究型芯收缩率、显气孔率和力学性能的变化,并观察试样断面微观形貌。结果表明,当氧化锆纤维掺入量从0增加到5%,陶瓷型芯试样的室温和1 550℃高温抗弯强度先上升后下降;当氧化锆纤维掺入量为1%时,室温和1 550℃高温抗弯强度最好,分别为18.64 MPa和28.06 MPa,与未纤维强化的陶瓷型芯试样对比,分别提升15.84%和13.46%;氧化锆纤维掺入量为1%的陶瓷型芯试样的收缩率为0.89%,显气孔率为30.4%,高温变形量为0.71mm。分析认为,氧化锆纤维掺入量较高导致纤维的完整性被破坏且出现团聚现象、对基体起割裂作用是陶瓷型芯试样综合性能变差的主要原因。 相似文献
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添加30wt%ZrSiO4硅基陶瓷型芯高温特性的研究 总被引:1,自引:0,他引:1
本文对添加30wt%ZrSiO_4硅基型芯试样在1200~1600℃时的热变形,抗弯强度、收缩率和型芯溶蚀性进行了研究。结果表明:在1550℃的热变形量激增,1350~1400℃的抗弯强度突降,前者因Al_2O_3与SiO_2形成的液相,后者主要与石英玻璃的大量析晶有关,收缩率随温度升高而增加而型芯溶蚀速度减小,是与型芯组织内的粘滞流动导致微观相之间孔隙减小,气孔率下降有关。 相似文献
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《铸造》2017,(12)
以球形SiO_2颗粒为基体、硅树脂为粘结剂,通过干压法制备多孔SiO_2陶瓷型芯,研究了硅树脂添加量和烧结温度对陶瓷型芯性能的影响。研究结果表明:硅树脂作为粘结剂通过交联、裂解从而实现对球形SiO_2颗粒的包覆和粘结,明显改善了球形SiO_2颗粒的烧结性能。在1 350℃烧结温度下,随着硅树脂含量增大,型芯样品的失重率不断增大,收缩率反而不断减小;在硅树脂含量为20%时,收缩率仅为0.42%,能较好地保证型芯的尺寸精度;硅树脂含量为10%时,在1 300℃烧结2 h,陶瓷型芯室温抗弯强度为11.8 MPa、线性收缩率为0.49%、显气孔率为30.9%,综合性能最佳。 相似文献
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在刚玉粉料中添加蓝晶石,利用原位合成方法制备了氧化铝基复合陶瓷型芯,讨论了蓝晶石含量以及烧结制度对氧化铝基复合型芯几种性能的影响.结果表明:烧结温度对氧化铝基复合陶瓷型芯蠕变性能影响较大,蓝晶石含量变化影响次之;随着蓝晶石含量增加,陶瓷型芯气孔率增加,线收缩率减小,线膨胀系数减小.随着烧结温度增加,陶瓷型芯气孔率减小,线收缩率增加. 相似文献
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粉料粒度对氧化铝基陶瓷型芯材料性能的影响 总被引:3,自引:0,他引:3
研究了精密铸造叶片用氧化铝基复合陶瓷型芯刚玉粉料粒度对型芯物相、形貌、气孔率、抗蠕变性能、脱芯性能的影响.研究结果表明:粉料粒度对Al2O3基复合陶瓷型芯材料的气孔率、线收缩率和高温蠕变性能均有影响.根据实验数据,分析了几种粉料粒度对陶瓷型芯综合性能影响的机理,同时讨论了不同粉料粒度型芯的烧结机理. 相似文献
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研究了精密铸造叶片用氧化铝基复合陶瓷型芯刚玉粉料粒度对型芯物相、形貌、气孔率、抗蠕变性能、脱芯性能的影响。研究结果表明:粉料粒度对Al2O3基复合陶瓷型芯材料的气孔率、线收缩率和高温蠕变性能均有影响。根据实验数据,分析了几种粉料粒度对陶瓷型芯综合性能影响的机理,同时讨论了不同粉料粒度型芯的烧结机理。 相似文献
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Effects of the debinding atmosphere, powder characteristic, solid loading and heating rate on the compact deformation were investigated. The compact strength after thermal debinding was measured by bending mode. The experimental results indicate that the vacuum atmosphere is beneficial to improving the deformation resistance compared with nitrogen atmosphere. Small particle size, irregular particle shape and high solid loading are suitable for decreasing the deformation defects. Besides, too fast heating rate may induce deformation defects. It is also indicated that effect of the factors for the deformation defects is different in different debinding stages. The strength evolution of the compacts during thermal debinding was also discussed. 相似文献
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Xiao-fu Liu Xin-li Guo Guo-yan Shui Chang-chun Li Gui-qiao Su Xun Sun Yang Guan Lei Jin 《中国铸造》2021,18(6):593-598
Fused corundum is a rather promising raw material for preparing an alumina-based ceramic core due to its excellent high temperature resistance and chemical inertness.In this study,alumina-based ceramic cores were prepared using fused corundum as the matrix material,and the effect of varying silica powder contents on the properties of the alumina-based ceramic cores,including the sintering shrinkage,the flexural strength,and the high temperature deformation was investigated.The mineralization mechanisms of the silica on the alumina-based ceramic core were also analyzed.The optimum addition amount of silica in this experiment is 8% in weight.At that moment,the aluminum-based core has both a low sintering shrinkage coefficient of 0.66% and better properties:the room temperature flexural strength is 22.19 MPa,the high temperature flexural strength is 21.54 MPa,the high temperature deformation is 0.93 mm,and the residual flexural strength is 47.41 MPa. 相似文献
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采用不同工艺制备了精密铸造用型芯及强度试样,并对型芯的抗弯强度及型芯、铸件合格率进行了研究.研究结果表明,1 100℃下烧结的型芯抗弯强度及型芯的成品率均高于1 050℃烧结型芯的抗弯强度及型芯的成品率.室温下经低温强化型芯的抗弯强度高于“高温+低温”复合强化型芯的抗弯强度,而单独进行高温强化的型芯的抗弯强度最小.在1 350℃下,经高温强化和低温强化型芯的抗弯强度均高于9 MPa.硅溶胶高温强化型芯在1 350℃下的抗弯强度远低于采用硅酸乙酯进行高温强化的型芯.采用硅溶胶高温强化1 100℃烧结出的空心型芯,具有较好的抗弯强度及退让性的组合,而且其成品率较高,同时该工艺可提高铸件的合格率,降低铸件裂纹率. 相似文献
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热变形对共晶铝硅合金铸件组织和性能的影响 总被引:1,自引:1,他引:0
对共晶铝硅合金铸造试样实施热塑性变形,考察了变形工艺对其组织和性能的影响规律。研究表明,热变形可以球化共晶硅颗粒,焊合缩孔、缩松,从而使合金铸态下的抗拉强度由205MPa提高到260MPa,伸长率由3·2%提高到10%;合金热处理后的抗拉强度由292MPa提高到397·4MPa,伸长率由0·5%提高到6·5%;分别提高36·1%和1200% 相似文献
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采用胶粘法制备大尺寸钢质泡沫铝夹心板,测试夹心板的三点弯曲强度,分析面板厚度、芯层厚度对夹心板弯曲性能的影响规律,研究弯曲载荷作用下的夹心板失效机理。结果表明:钢质泡沫铝夹心板可承受很高的弯曲载荷,夹心板抗弯强度随着芯层泡沫铝厚度的提高而提高。增加钢面板的厚度,夹心板抗弯强度整体呈增强趋势。当面板厚度为8 mm、芯层厚度为50 mm时,夹心板的极限抗弯强度可达66.06 kN。芯层泡沫铝内泡壁表面的大尺寸裂纹是夹心板在弯曲载荷作用下失效的主要原因;采用熔体发泡法制备的泡沫铝板材,因冷却强度过大而导致的附加应力使泡壁的强度下降,也是影响夹心板力学性能的主要因素。 相似文献
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钛合金精密铸造陶瓷型芯 总被引:1,自引:0,他引:1
利用挤压成型的方法,制备了应用于钛合金高尔夫球杆头精密铸件的陶瓷型芯。研究了型芯的抗压强度、抗弯强度、热膨胀性能及型芯与钛液的界面反应特性。结果表明,氧化锆陶瓷型芯的物理性能能够满足钛合金高尔夫球杆头铸造要求,该陶瓷型芯与钛合金液不发生明显的界面反应。 相似文献
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《中国铸造》2020,(5)
In order to improve the performance of plaster molds for investment casting,a diverse content of glass fiber and polypropylene (PP) fiber was incorporated into the slurry for the preparation of a fiber-reinforced mold.The green and fired bending strengths,thermal expansion properties,permeability,and thermal shock resistance of the mold were examined,and the scanning electron microscope (SEM) with energy dispersive spectrometer (EDS) was applied for the observation of fracture morphology.With appropriate content,the introduction of glass fiber was proved to increase the green bending strength and fired bending strength,restrain the thermal expansion and improve the thermal shock resistance of the mold,while the polypropylene fiber added was able to raise the green bending strength and the permeability,reduce the thermal expansion and heighten the thermal shock resistance as well,though the fired bending strength would be weakened slightly.Evenly distributed fibers were capable of enhancing the mechanical properties of the matrix,but agglomerations and bundles of fibers resulting from excessive addition had a negative impact.Meanwhile,it was also manifested that micropores left by ablative polypropylene fibers could improve the permeability and reduce the thermal expansion of the mold,and the fired bending strength would be decreased slightly by the deterioration of continuous structure.Three different ratios of hybrid fiber were employed in plaster molds,which can meet altered requirement of castings.The samples modified with hybrid fiber possessed lower thermal deformation,higher air permeability,and better resistance of thermal shock,while the mechanical strength was equal to the fiber free sample or slightly increased. 相似文献
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烧结工艺对多孔材料性能有很大的影响,为了获得最佳的力学性能和需要的零件形状,有必要对烧结的热变形过程进行研究。基于SVOS粘塑性本构模型,采用热力耦合计算不锈钢多孔材料在烧结过程中宏观变形。通过自由烧结实验和弯曲实验,使用4阶Gauss函数对烧结应力、体积和剪切粘度等模型参数进行了拟合。讨论了相对密度、线性收缩率等随烧结时间和温度的变化规律。结果表明:模拟过程与实验符合得较好,验证了模型的合理性。不同升温速率下,材料的线性收缩曲线变化不大,因此,升温速率对烧结过程影响较小。升温速率对计算时间影响比较大,升温速率很慢或很快时,计算不容易收敛,计算时间比较长。对模压生坯零件的烧结模拟结果表明,由于初始密度分布不均匀性导致最终密度分布的不均匀,但是密度变化范围不大。 相似文献
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压铸模具型芯变形失效的研究分析 总被引:6,自引:0,他引:6
压铸模具的型芯变形失效很容易造成铸件的成批量报废.文中对于一失效型芯进行了分析研究,结果表明,其弯曲变形是由于受到不断循环的热作用及金属液的冲击所造成的微小变形积累造成的;同时,型芯的硬度在不同的部位均有下降,其中在冲击部位下降幅度最大.型芯在与铝液接触的表面会形成过渡层,圆形的型芯横截面会发生变形.采取有效的措施是可以避免田型芯弯曲变形所造成的铸件成批量报废的. 相似文献