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全膝关节置换过程中挤压驱血和抬腿驱血与置换后并发症的关系 预览
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作者 尹健东 王鑫灵 +1 位作者 左彪 李秾杙 《中国组织工程研究》 CAS 北大核心 2020年第9期1331-1336,共6页
背景:目前挤压驱血法广泛应用于全膝关节置换过程中。有研究表明,挤压驱血法有加重术后早期疼痛及增加术后并发症的风险,因此临床上急需一种能替代它的更加安全有效的驱血方法。目的:探讨全膝关节置换过程中使用抬腿驱血法和挤压驱血法... 背景:目前挤压驱血法广泛应用于全膝关节置换过程中。有研究表明,挤压驱血法有加重术后早期疼痛及增加术后并发症的风险,因此临床上急需一种能替代它的更加安全有效的驱血方法。目的:探讨全膝关节置换过程中使用抬腿驱血法和挤压驱血法对临床效果的影响。方法:将拟行初次单侧全膝关节置换的64例患者随机分为2组,置换过程中对照组采用挤压驱血,试验组采用抬腿驱血。术后比较2组患者的主要观察指标:目测类比评分、膝关节肿胀度、C-反应蛋白、血清肌酸激酶活性及术后并发症等;次要观察指标:止血带使用时间、美国特种外科医院评分、SF-36评分等。结果与结论:①术后第4,7天及第1,3个月,试验组目测类比评分显著低于对照组(P<0.05);②术后2组的C-反应蛋白水平、血清肌酸激酶活性及膝关节肿胀度均有升高,但试验组的升高程度明显低于对照组(P<0.05);③在术后并发症方面,术后对照组在张力水泡及深静脉血栓发生率上高于试验组(P<0.05),且对照组的总并发症发生率显著高于试验组(P<0.05);④2组止血带的使用时间差异无显著性意义(P>0.05);⑤随访第4,3,6个月评估美国特种外科医院评分及SF-36评分,结果显示较术前均有所改善,但组间比较差异无显著性意义(P>0.05);⑥说明全膝关节置换过程中抬腿驱血可减轻术后早期疼痛反应,降低机体的炎症反应及患膝软组织损伤,减少皮肤张力性水泡、血栓栓塞等并发症的发生率,符合快速康复的理念要求。因此在全膝关节置换过程中抬腿驱血是一种比挤压驱血更加安全有效的驱血方法。 展开更多
关键词 全膝关节置换 止血带 抬腿驱血 挤压驱血 术后早期疼痛 并发症 快速康复
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钛合金弯管动态流量控制法挤压成形的模拟与实验研究 预览
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作者 石磊 文九巴 +3 位作者 姚怀 贺俊光 吴武伟 廖桂华 《中国有色金属学报》 EI CAS CSCD 北大核心 2019年第2期380-387,共8页
通过有限元分析和实验研究动态流量控制法挤压钛合金弯管件。实验验证弯管的尺寸精度和挤压载荷。分析调控量对弯曲曲率的影响、速度场和温度场。结果表明:挤压载荷的峰值误差为14.51%,挤出的管材弯曲曲率误差为3.47%;在模具结构中,调... 通过有限元分析和实验研究动态流量控制法挤压钛合金弯管件。实验验证弯管的尺寸精度和挤压载荷。分析调控量对弯曲曲率的影响、速度场和温度场。结果表明:挤压载荷的峰值误差为14.51%,挤出的管材弯曲曲率误差为3.47%;在模具结构中,调控通道Ⅱ截面面积不变时,弯管曲率半径随调控通道Ⅰ有效截面面积的增大而增大;在定径带处的合金呈非均匀流动,弯管件内外弧面存在流速差是挤出弯曲件的原因;合金的流速在通过定径带时发生分流补偿,由调控通道Ⅱ进入定径带的合金流速反超辅助通道内的流速,在焊合腔内边缘处存在金属流动死区。在定径带区域温升明显,最大温升为134℃。 展开更多
关键词 弯管 挤压 动态流量调控 钛合金
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同步挤压广义S变换在南海油气识别中的应用 被引量:1
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作者 严海滔 黄饶 +2 位作者 周怀来 牛聪 邬蒙蒙 《地球物理学进展》 CSCD 北大核心 2019年第3期1229-1235,共7页
受窗函数的影响,短时傅里叶变换、小波变换、S变换等传统时频分析方法的分辨率不高.为了提高信号时频变换分辨率,发展了同步挤压小波变换算法;该算法将信号的时频谱值向其中心频率位置挤压,改善了信号时频分析结果,使得信号时频分辨率... 受窗函数的影响,短时傅里叶变换、小波变换、S变换等传统时频分析方法的分辨率不高.为了提高信号时频变换分辨率,发展了同步挤压小波变换算法;该算法将信号的时频谱值向其中心频率位置挤压,改善了信号时频分析结果,使得信号时频分辨率得到了很大的提升.但由于传统算法时窗固定,处理缺乏灵活性;因此,本文对S变换窗函数进行扩展,提出了同步挤压广义S变换.通过自适应窗函数挤压信号在S域的时频谱值,提高了算法的灵活性和时频分析聚焦能力.运用同步挤压广义S变换对南海某工区实际地震数据进行分频处理,结果显示含油气层能量随着频率的增加而逐渐衰减.因此,使用同步挤压广义S变换对地震数据进行分析处理,不仅可以对储层含油气性进行准确的检测,还可以对地层进行精确的标定. 展开更多
关键词 窗函数 小波变换 挤压 同步挤压广义S变换
模具工作带微角度对型材表面挤压纹的影响 预览
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作者 郑云鹏 《轻合金加工技术》 CAS 北大核心 2019年第1期48-51,61共5页
主要通过三种不同角度工作带模具挤出型材表面挤压纹的对比试验,探讨了模具工作带微角度变化对工作带粘铝附着层和型材表面挤压纹的影响。建立数学模型,推算出合理的模具工作带微阻碍角,提出了改善挤压纹和提高模具通过量的有效途径。
关键词 挤压 模具 工作带 微角度 挤压纹
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Aging Behaviours of 8011 Al and 8011 Al/15% SiCp Composites 预览
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作者 V. Vembu 《矿物质和材料特性和工程(英文)》 2019年第5期221-229,共9页
In this investigation, the effect of aging on the hardness and tensile behavior of 15% SiCp/8011 Al composites has been studied. The composites were manufactured through stir casting method. Cast ingots of the composi... In this investigation, the effect of aging on the hardness and tensile behavior of 15% SiCp/8011 Al composites has been studied. The composites were manufactured through stir casting method. Cast ingots of the composites were hot extruded at 500&deg;C. The composite samples were solution heat-treated at 530°C for 3 h and quenched in cold water. The aging temperature was 130°C, 150°C, 170°C, 190°C, and 210°C for aging duration of 1, 3, 5, 7 and 9 hrs respectively. The mechanical properties measured included: tensile strength, yield strength and hardness values. The composites produced exhibited maximum mechanical properties at peak aged condition. These increases in mechanical properties during aging are attributed to the formation of coherent and uniform distribution SiC particles in the aluminum matrix composites. It was also observed that thermal modification plays an important role in retaining the ductility of composites. This result shows that a substantial improvement in mechanical properties has been achieved in the reinforced metal matrices produced after age-hardening. 展开更多
关键词 8011 Aluninum Matrix Composite EXTRUSION AGING Behavior Tensile Strength Micro Hardness Response Surface Methodology (RSM)
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Effect of Extrusion Temperatures on Friction-wear Behavior of Chain-wheel Fabricatetl by 40Cr Steel under Oil-lubrication Condition
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作者 陈海翔 LIU Wei 孔德军 《武汉理工大学学报:材料科学英文版》 SCIE EI CAS 2019年第3期684-691,共8页
A 40Cr steel was formed into a chain-wheel using a warm extrusion technology. The surface roughness and micro-structure, micro-hardness and phases of the extruded samples at different temperatures were analyzed using ... A 40Cr steel was formed into a chain-wheel using a warm extrusion technology. The surface roughness and micro-structure, micro-hardness and phases of the extruded samples at different temperatures were analyzed using a three-dimensional optical microscope (OM), micro-hardness tester, and X-ray diffraction (XRD), respectively. The morphologies, chemical element distributions and phases of worn tracks at the extrusion temperatures of 550, 650 and 750 °C were analyzed using a scanning electron microscopy (SEM), energy disperse spectroscopy (EDS), and XRD, respectively. The friction-wear behaviors of extruded samples under oil-lubrication condition were observed using a wear test. And the effects of extrusion temperatures on the wear mechanism were discussed. The results show that residual austenite and pearlite exist on the sample at the extrusion temperature of 550 °C with the corresponding grain size and surface micro-hardness of 32.7 nm and 370.33 HV, respectively. The average coefficient of friction (COF) of extruded sample at the temperature of 550 °C is 0.196 5, and the wear mechanism is fatigue and abrasive wear. While the acicular martensite exists on the extruded samples at the extrusion temperatures of 650 and 750 °C, the corresponding grain sizes are 30.0 and 29.1 nm, respectively. The average COF (coefficient of friction) of extruded sample at the temperatures of 650 and 750 °C are 0.187 4 and 0.163 6, respectively, and the wear mechanism is abrasive wear. As a result, the friction performance of extruded sample at the temperatures of 650 and 750 °C is better than that at the temperature of 550 °C. 展开更多
关键词 WARM EXTRUSION 40Cr steel EXTRUSION temperature coefficient of FRICTION (COF) WEAR mechanism
Reduction of die roll height in duplex gears through a sheet-bulk metal forming method
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作者 Xiao-Long Sun Xin-Cun Zhuang +1 位作者 Feng-Chun Yang Zhen Zhao 《先进制造进展:英文版》 CAS CSCD 2019年第1期42-51,共10页
In the existing shearing processes for fabricating parts such as duplex gears, die roll is difficult to avoid. Accordingly, a method based on sheet-bulk metal forming for fabricating a duplex gear with extremely small... In the existing shearing processes for fabricating parts such as duplex gears, die roll is difficult to avoid. Accordingly, a method based on sheet-bulk metal forming for fabricating a duplex gear with extremely small die roll in one stroke is proposed in the current work. The process could be divided into three stages according to the forming features: upsetting and shearing stage, lateral extrusion stage, and local filling stage. The die roll appeared in the shearing stage, which could be reduced in the subsequent extrusion and local filling stages. To reveal the underground mechanism, material flows under two situations, as a key factor to influence the forming quality, were compared and investigated. The results revealed that by controlling material flow, one could avoid the defects and reduce the die roll. 展开更多
关键词 DIE ROLL DUPLEX gear part Sheet-bulk metal forming Lateral extrusion Material flow
Microstructure and Mechanical Properties of AZ31 Mg Alloy Fabricated by Pre-compression and Frustum Shearing Extrusion
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作者 Kun Sheng Li-Wei Lu +2 位作者 Yao Xiang Min Ma Zhong-Chang Wang 《金属学报:英文版》 SCIE EI CAS CSCD 2019年第2期235-244,共10页
The AZ31 Mg alloys were processed by 6% pre-compression and frustum shearing extrusion at various temperatures, and the microstructure, texture and mechanical properties of the resulting alloys are systematically inve... The AZ31 Mg alloys were processed by 6% pre-compression and frustum shearing extrusion at various temperatures, and the microstructure, texture and mechanical properties of the resulting alloys are systematically investigated. The results show that the grain size monotonically increases from 6.4 to 12.6 lm and the texture intensity increases from 6.7 to 9.6with the increase in the extrusion temperature. The combining effect of the pre-twinning and the frustum shearing deformation is found to contribute to the development of the weak basal texture in Mg alloys. The Mg alloy sheet produced at the extrusion temperature of 563 K exhibits excellent mechanical properties. The yield strength, ultimate tensile strength and elongation for the extruded alloys are 189.6 MPa, 288.4 MPa and 24.9%, respectively. Such improved mechanical properties are comparable or even superior to those of the alloys subjected to other deformation techniques, rendering the pre-compression and frustum shearing extrusion a promising way for further tailoring properties of Mg alloys. 展开更多
关键词 AZ31 MAGNESIUM alloy Frustum SHEARING EXTRUSION Microstructure Mechanical property Dynamic RECRYSTALLIZATION
Extrusion process of 304L H-shaped stainless steel used in passive residual heat removal heat exchanger 预览
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作者 Lei-Feng Tuo Gen-Shu Zhou +2 位作者 Zhi-Qiang Yu Xi-Tang Kang Bo-Wen Wang 《核技术:英文版》 SCIE CAS CSCD 2019年第4期70-79,共10页
304L H-shaped stainless steel is used as the support frame of the passive residual heat removal heat exchanger (PRHR HX) in a nuclear fission reactor. The extrusion process is adopted to manufacture the 304L H-shaped ... 304L H-shaped stainless steel is used as the support frame of the passive residual heat removal heat exchanger (PRHR HX) in a nuclear fission reactor. The extrusion process is adopted to manufacture the 304L H-shaped stainless steel. Finite element method simulation is herein used to analyze metal flow characteristics, optimize the extrusion die, and predict the extrusion force at different temperatures and speeds. A Ф400-mm container and Ф388-mm forging billet are selected, and the 304L H-shaped stainless steel is successfully manufactured using a Germany SMS 60 MN horizontal extruder. The mechanical properties and microstructure of the manufactured 304L H-shaped stainless steel meet the requirements of the PRHR HX, and the surfaces of the product pass the dye penetration test. The H-shaped stainless steels are used in Haiyang nuclear power plant in Shandong Province. 展开更多
关键词 PRHR HX Support frame EXTRUSION process 304L H-shaped STAINLESS steel
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淀粉塑料的加工成型研究进展 预览
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作者 周文 陈春昊 +3 位作者 银鹏 郭斌 黄亚男 李盘欣 《塑料工业》 CAS CSCD 北大核心 2019年第8期1-6,共6页
进入21世纪以来,人们对于环境保护的认识逐渐提高,能源枯竭,资源消耗等问题已经引起整个社会广泛的关注,使用可生物降解的环境友好材料代替石油基塑料已经成为当前研究的热点。天然淀粉具有可完全生物降解、价格低廉、可再生、来源广泛... 进入21世纪以来,人们对于环境保护的认识逐渐提高,能源枯竭,资源消耗等问题已经引起整个社会广泛的关注,使用可生物降解的环境友好材料代替石油基塑料已经成为当前研究的热点。天然淀粉具有可完全生物降解、价格低廉、可再生、来源广泛等优点,因此,研究和开发淀粉塑料及其制品对推动可持续发展具有重要意义。从常用的加工成型方法出发,综述了目前淀粉塑料加工成型方法和工艺的研究进展,并对其未来的发展趋势进行了展望。 展开更多
关键词 淀粉塑料 挤出 溶液浇铸 加工成型 研究进展
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基于EtherCAT总线技术的押出机传动系统设计 预览
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作者 光宝科技工业自动化PM 赖政吉 吕佑彬 《变频器世界》 2019年第6期111-112,共2页
系统利用光宝EtherCAT现场总线通讯协议格式,实现光宝controller与EV08000变频器的通讯,完成押出机稳定的恒压控制、塑料挤出量稳定、以及材料的冷却、拉伸保持平整,满足押出机生产的工艺需要。
关键词 押出机 ETHERCAT 通讯
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小麦麸皮挤压膨化工艺研究 预览
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作者 任顺成 王凤雯 李丹 《河南工业大学学报:自然科学版》 CAS 北大核心 2019年第4期59-63,共5页
以麦麸为原料,麦麸水分含量、机筒末端温度、螺杆转速、喂料速度为考察参数,采用单因素、正交试验对麦麸进行最优挤压膨化工艺参数研究。得出最佳工艺参数为:水分含量27.5%、螺杆转速9Hz、机筒末端温度145℃、喂料速度9kg/h,麦麸在此参... 以麦麸为原料,麦麸水分含量、机筒末端温度、螺杆转速、喂料速度为考察参数,采用单因素、正交试验对麦麸进行最优挤压膨化工艺参数研究。得出最佳工艺参数为:水分含量27.5%、螺杆转速9Hz、机筒末端温度145℃、喂料速度9kg/h,麦麸在此参数挤压后的总膳食纤维和可溶性膳食纤维含量分别提高了11.69、1.16个百分点。扫描电镜下可观察到疏松多孔的结构、凹凸不平的表面和增大的裸露表面积,这与其具有高膨胀力和高持水性相一致,说明挤压膨化后的麦麸其可食性、功能性以及营养性将会得到明显改善。 展开更多
关键词 麦麸 挤压膨化 理化特性 扫描电镜
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A Potential Model for Detecting Crowding-induced Epithelial Cell and Cancer Cell Extrusion 预览
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作者 Ping HAN Dong-xiao LI +6 位作者 Yu LEI Jing-mei LIU Xiang-ming DING Han WANG Zhuo-ying LIN Wei YAN De-an TIAN 《当代医学科学(英文)》 SCIE CAS 2019年第3期391-395,共5页
Overcrowding and cell deformation lead to the shedding of apoptotic and live cells to maintain homeostasis in the epithelium. Recent studies have attempted to explain the effect of extrusion on epithelial homeostasis ... Overcrowding and cell deformation lead to the shedding of apoptotic and live cells to maintain homeostasis in the epithelium. Recent studies have attempted to explain the effect of extrusion on epithelial homeostasis and tumor metastasis, but lack the requisite quantitative models for testing extrusion. Here, we designed a petri dish inversion model to detect the extrusion ability of both normal epithelial cells and epithelial cancer cells. Firstly, we found cell extrusion was observed in both normal epithelial cells (LO2 cells) and cancer cells;in confluent LO2 cell culture, certain cells were surrounded by their neighbors, suffered "collective attack", and were then made round in shape. Green fluorescent protein (GFP)-labeled cancer cells were also found to be squeezed by normal LO2 cells. Using the petri dish inversion model, we quantified the number of extrusion cells, and demonstrated that the ability of cancer cell extrusion was related to the metastatic potential of cancer cell lines. Our findings provide a novel model to detect crowdinginduced epithelial cell and cancer cell extrusion. This novel model provides a quantitative method for research into apoptotic and cancer cell extrusion, particularly in human hepatocellular carcinoma. 展开更多
关键词 hepatocellular carcinoma metastasis epithelial HOMEOSTASIS CROWDING EXTRUSION
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Zn添加对Mg-8Al-2Sn镁合金组织和力学性能的影响
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作者 伍华怡 张丁非 +3 位作者 蒋璐瑶 冯靖凯 赵阳 潘复生 《稀有金属材料与工程》 SCIE EI CAS CSCD 北大核心 2019年第7期2091-2098,共8页
以Mg-8Al-2Sn变形镁合金为研究背景,通过在Mg-8Al-2Sn合金中添加0%~2%(质量分数,下同)的Zn元素,研究了Zn添加对Mg-8Al-2Sn挤压镁合金显微组织和性能的影响。结果表明,铸态Mg-8Al-2Sn-XZn合金的相组成主要是α-Mg相、Mg17Al12相和Mg2Sn... 以Mg-8Al-2Sn变形镁合金为研究背景,通过在Mg-8Al-2Sn合金中添加0%~2%(质量分数,下同)的Zn元素,研究了Zn添加对Mg-8Al-2Sn挤压镁合金显微组织和性能的影响。结果表明,铸态Mg-8Al-2Sn-XZn合金的相组成主要是α-Mg相、Mg17Al12相和Mg2Sn相。在添加Zn元素以后,合金中的共晶化合物的形态发生变化,由共晶组织变为离异共晶组织。挤压过后,晶粒组织尺寸更均匀。Zn元素的加入,会促进合金中第二相在挤压过程中的动态析出以及第二相的粗化。合金在时效中产生的析出相的数量也随着Zn含量的增多而增加。随着Zn含量的增加,挤压态和时效态合金的屈服强度和抗拉强度都随之增加。当Zn含量达到2%时,合金力学性能最好,其时效态的抗拉强度,屈服强度和延伸率分别是385 MPa,291 MPa和6.44%。 展开更多
关键词 镁合金 Mg-Al-Sn-Zn挤压镁合金 显微组织 力学性能
活塞杆加工工艺研究与应用 预览 被引量:1
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作者 武泾元 王宇驰 张健 《新技术新工艺》 2019年第2期28-31,共4页
在高压电气产品中,活塞杆类零件属于关键零件,且应用较多。这类零件的特点是细长、一端粗以及含深孔加工。这类零件常用的加工方式是用棒料直接加工成形,这种加工工艺材料利用率低,工艺性差。针对上述问题,研究采用双肘杆镦锻工艺和挤... 在高压电气产品中,活塞杆类零件属于关键零件,且应用较多。这类零件的特点是细长、一端粗以及含深孔加工。这类零件常用的加工方式是用棒料直接加工成形,这种加工工艺材料利用率低,工艺性差。针对上述问题,研究采用双肘杆镦锻工艺和挤压工艺进行加工,这样可节省材料和加工时间,降低制造成本。分别分析了棒料直接加工、双肘杆镦锻工艺和挤压工艺等3种加工工艺的优缺点,并开展了双肘杆镦锻和挤压模具设计、成形工艺研究和工艺验证。 展开更多
关键词 活塞杆 深孔钻 双肘杆 镦锻 调质 挤压
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工程重组米的研究进展 预览 被引量:1
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作者 沈宇光 肖志刚 +3 位作者 柴媛 王丽爽 杨柳 杨国强 《农产品加工》 2019年第2期63-65,70共4页
为了使健康营养的重组米早日进入人们的视野,论述了重组米发展历程、近几十年的研究进展及加工方法,为重组米领域的科研工作者深层次研究提供借鉴和参考。
关键词 重组米 挤压 淀粉 营养 速食米
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燕麦麸膳食纤维挤出改性工艺
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作者 刘静雪 李凤林 +3 位作者 王英臣 史海慧 史亚楠 谭秀环 《食品工业》 CAS 北大核心 2019年第5期21-24,共4页
以燕麦麸皮为原料,利用双螺杆挤出法对燕麦麸皮进行改性处理,比较挤压前后可溶性膳食纤维的含量变化,采用单因素和正交试验优化挤出改性工艺参数。结果表明:对改性燕麦麸膳食纤维SDF含量影响因素大小依次为水分添加量>燕麦麸粉粒度&... 以燕麦麸皮为原料,利用双螺杆挤出法对燕麦麸皮进行改性处理,比较挤压前后可溶性膳食纤维的含量变化,采用单因素和正交试验优化挤出改性工艺参数。结果表明:对改性燕麦麸膳食纤维SDF含量影响因素大小依次为水分添加量>燕麦麸粉粒度>螺杆转速>挤出温度,双螺杆挤压法改性膳食纤维最佳工艺参数为水分添加量26%、挤出温度75℃、燕麦麸粉粒度140目、双螺杆转速24 Hz。在该最佳工艺条件下,改性燕麦麸膳食纤维中SDF可达8.8%,比原燕麦麸膳食纤维中SDF提高29.4%。 展开更多
关键词 燕麦麸 膳食纤维 挤出 改性
流动性在胶料工业化性能控制中的应用 预览
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作者 邓世涛 刘华侨 +2 位作者 李涛 顾培霜 朱家顺 《轮胎工业》 CAS 2019年第11期643-646,共4页
在工业化生产条件下研究门尼粘度和流动性在胶料加工性能控制中的应用。结果表明,基于低剪切速率测试条件下的门尼粘度无法准确表征胶料的流动性,流动性测试的剪切速率范围涵盖压延、挤出加工条件下胶料的真实工况,更能真实表征胶料的... 在工业化生产条件下研究门尼粘度和流动性在胶料加工性能控制中的应用。结果表明,基于低剪切速率测试条件下的门尼粘度无法准确表征胶料的流动性,流动性测试的剪切速率范围涵盖压延、挤出加工条件下胶料的真实工况,更能真实表征胶料的工业化性能。同时,胎侧胶和胎圈胶的挤出状态与门尼粘度和流动性的相关性试验也表明了流动性在胶料工业化性能控制中的优势。 展开更多
关键词 胶料 门尼粘度 流动性 工业化性能 挤出
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Evolution of Microstructure, Residual Stress, and Tensile Properties of Mg–Zn–Y–La–Zr Magnesium Alloy Processed by Extrusion
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作者 Huseyin Zen gin Yunus Turen +1 位作者 Muhammet Emre Turan Fatih Aydin 《金属学报:英文版》 SCIE EI CAS CSCD 2019年第11期1309-1319,共11页
The microstructure, texture, residual stress, and tensile properties of Mg–6 Zn–2 Y–1 La–0.5 Zr(wt%) magnesium alloy were investigated before and after extrusion process, which performed at 300 °C and 400 ... The microstructure, texture, residual stress, and tensile properties of Mg–6 Zn–2 Y–1 La–0.5 Zr(wt%) magnesium alloy were investigated before and after extrusion process, which performed at 300 °C and 400 °C. The microstructural characterizations indicated that the as-cast alloy was comprised of α-Mg, Mg–Zn, Mg–Zn–La, and Mg–Zn–Y phases. During homogenization at 400 °C for 24 h, most of the secondary phases exhibited partial dissolution. Extrusion process led to a remarkable grain refi nement due to dynamic recrystallization(DRX). The degree of DRX and the DRXed grain size increased with increasing extrusion temperature. The homogenized alloy did not show a preferential crystallographic orientation, whereas the extruded alloys showed strong basal texture. The extrusion process led to a signifi cant improvement on the compressive residual stress and mechanical properties. The alloy extruded at 300 °C exhibited the highest basal texture intensity, the compressive residual stress and hardness, and yield and tensile strengths among the studied alloys. 展开更多
关键词 ZK60 Magnesium alloy Residual stress TEXTURE Mechanical properties EXTRUSION
Thermal Conductivity and Tensile Properties of Carbon Nanofiber-Reinforced Aluminum-Matrix Composites Fabricated via Powder Metallurgy: Effects of Ball Milling and Extrusion Conditions on Microstructures and Resultant Composite Properties
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作者 Fumio Ogawa Shuji Yamamoto Chitoshi Masuda 《金属学报:英文版》 SCIE EI CAS CSCD 2019年第5期573-584,共12页
Carbon nanofiber(CNF)-reinforced aluminum-matrix composites were fabricated via ball milling and spark plasma sintering(SPS), SPS followed by hot extrusion and powder extrusion. Two mixing conditions of CNF and alumin... Carbon nanofiber(CNF)-reinforced aluminum-matrix composites were fabricated via ball milling and spark plasma sintering(SPS), SPS followed by hot extrusion and powder extrusion. Two mixing conditions of CNF and aluminum powder were adopted: milling at 90 rpm and milling at 200 rpm. After milling at 90 rpm, the mixed powder was sintered using SPS at 560℃. The composite was then extruded at 500℃ at an extrusion ratio of 9. Composites were also fabricated via powder extrusion of powder milled at 200 rpm and 550℃ with an extrusion ratio of 9(R9) or 16(R16). The thermal conductivity and tensile properties of the resultant composites were evaluated. Anisotropic thermal conductivity was observed even in the sintered products. The anisotropy could be controlled via hot extrusion. The thermal conductivity of composites fabricated via powder extrusion was higher than those fabricated using other methods. However, in the case of specimens with a CNF volume fraction of 4.0%, the thermal conductivity of the composite fabricated via SPS and hot extrusion was the highest. The highest thermal conductivity of 4.0% CNF-reinforced composite is attributable to networking and percolation of CNFs. The effect of the fabrication route on the tensile strength and ductility was also investigated. Tensile strengths of the R9 composites were the highest. By contrast, the R16 composites prepared under long heating duration exhibited high ductility at CNF volume fractions of 2.0% and 5.0%. The microstructures of composites and fracture surfaces were observed in detail, and fracture process was elucidated. The results revealed that controlling the heating and plastic deformation during extrusion will yield strong and ductile composites. 展开更多
关键词 Al composite Carbon NANOFIBER Ball MILLING Hot EXTRUSION Microstructure and performance
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