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半固态浆料制备技术发展动向及其对策 总被引:7,自引:0,他引:7
以半固态金属流变成型技术为依托,论述了半固态浆料的质量要求和浆料制备新工艺,并针对浆料制备的关键技术(半固态浆料制备工艺和设备、新型材料设计和等轴非枝晶的形成机理)提出了建议性对策。 相似文献
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半固态加工技术的进展、前景及对策 总被引:4,自引:0,他引:4
半固态金属成形技术具有高效,节能,近终形生产和成形件性能高等许多优点,被专家们称为21世纪最具前景的加工方法,介绍了半固态金属成形的成形工艺,坯料制备工艺,微观组织,数值模拟状况,国内外研究应用情况,展望了半固态金属的前景,并提出了应对措施。 相似文献
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半固态金属加工是近年来金属加工技术研究的热点,因为它具有一系列优点,最突出的是半固态材料的触变性,成形的零件精度高、质量好,能与净近成形或净终成形(Near-net-shape)接轨。本文详细阐述了半固态金属成形特点和半固态金属制品的力学特性,同时还介绍了半固态技术在工业中的应用。 相似文献
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金属半固态铸造成形技术 总被引:2,自引:0,他引:2
金属的半固态铸造是近年来出现的一种新的铸造加工成形方法。该方法与传统的全液态铸造相比,具有节约能源、生产率高、产品质量好等优点。本文介绍了半固态金属浆料的制备方法,半固态压铸、半固态连铸等金属半固态铸造成形技术,并指出了存在的问题及进一步研究工作。 相似文献
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1前言 半固态金属成形主要用于对铝合金和镁合金等轻金属的加工。到目前为止,半固态金属成形一直被用来制造此类合金的各种金属部件,如汽车和移动电话的配件。对于轻金属半固态成形的绝大多数研究的目的是为了揭示轻金属合金半固态成形实用技术发展的基本特征。相比之下,对包括不锈钢在内的铁基合金半固态成形的研究还非常少,这可能是由于此类合金具有较高的熔点、较窄的半固态温度区间以及在凝固和重熔过程中发生复杂的γ←→δ相变。对铁基合金半固态成形工艺进行优化需要了解其在半固态时的材料特性。这些特性在半固态温度区间内受到材料显微结构变化的显著影响。对于铁基合金半固态成形的研究仍处于基础阶段。 相似文献
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采用流变成型法制备了半固态ZA27—16Vol%Si合金,与常规铸造合金进行了对比,并对其摩擦特性进行了研究,为锌铝合金的半固态加工新技术提供了理论依据。 相似文献
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It has been more than ten years since the semi-solid processing (SSP) technique was put into commercial ap plications in the world. A lot of work on semi-solid metals (SSM) including their preparation, reheating and semi-solid forming has been done in China. In order to produce the high quality die-casting, a novel innovation that modifies the present machines based on the SSP technique was proposed. Semi-solid die-casting on modified casting machines can manufacture parts with more excellent quality than those produced by squeeze casting. It was found that the defects such as "elephant foot" and "periphery liquid metal loss" during reheating could be avoided through controlling the non-de ndritic structure of billets and optimizing the reheating process. The processing parameters and mold designs of semi-so lid die-casting are fairly different from those of liquid die-casting. 相似文献
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G. Vijh A. Gokhale S. Mishra V. Singh N. N. Viswanathan 《Transactions of the Indian Institute of Metals》2009,62(4-5):291-294
A heat transfer model has been developed to simulate the evolution of temperature during semi-solid metal (SSM) solid freeform fabrication (SFF) process. The governing equations were solved numerically using finite difference method. Deposition of simple cubic components of A356 (Al-7%Si-0.45%Mg) aluminum alloy have been simulated. The effect of process parameters such as deposition pattern, deposition velocity, slurry cross-section and slurry temperature on the transient temperature distribution in these components have been studied. Out of the three deposition patterns studied, i.e. rotating, alternating and unidirectional, the alternating pattern enabled depositing larger interface-free components. Increasing the slurry flow rate resulted in the deposition of larger interface-free components. 相似文献
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半固态浆料液相的凝固行为决定了其二次凝固组织,这将直接影响半固态成形件的性能.Mg-Al系镁合金随着成分、凝固行为的不同,其二次凝固组织有较大的不同.该文描述了Mg-Al系合金半固态浆料液相凝固过程以及二次凝固组织特征,并针对其特征对其形成原因展开了分析. 相似文献
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M. Ramadan 《Transactions of the Indian Institute of Metals》2012,65(5):479-483
The microstructure of 1.4?% carbon steel produced either by ordinary casting or semi-solid casting with different primary fraction of solids using cooling plate technique was investigated. The microstructure of ordinary ultrahigh-carbon steel (O-UHCS), was improved by the semi-solid processing. Grain boundary cementite thickness of UHCS and its morphology is affected by semi-solid process. Grain boundary cementite thickness of about 2???m can be achieved by pouring the semi-solid slurry with 0.31 fraction of solid. The pearlitic interlamellar spacing of semi-solid processed UHCS is shorter compared to O-UHCS. 相似文献
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Dush David M.; Hirt Michael L.; Schroeder Harold E. 《Canadian Metallurgical Quarterly》1989,106(1):97
Reviews 48 outcome studies that applied self-statement modification (SSM) to childhood behavior disorders. Selection criteria restricted the review to controlled experimental studies and to children with disorders of clinically relevant severity. Meta-analysis was used to provide summary information about the observed effects of SSM. Collectively, SSM outcomes surpassed no treatment and placebo treatment by roughly a half of a standard deviation, on the average. Efficacy varied considerably with length of follow-up, experience level of therapists, age of children, outcome content area, and a number of other clinical and methodological differences among the studies. These qualifiers of observed efficacy are summarized and discussed in terms of implications for further research and application of SSM in child psychotherapy. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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K Iida K Fujita H Hirai H Goto S Miyazaki Y Arai H Iwaki M Otake S Sassa M Maemura T Nakayama H Kudo S Sakamoto 《Canadian Metallurgical Quarterly》1997,21(5):476-482
Polysaccharides extracted from human tubercle bacilli (specific substance of Maruyama [SSM]) have been clinically applied with satisfactory results. Thymidylate synthetase (TS) and thymidine kinase (TK) are key enzymes in de novo and salvage pathways for pyrimidine nucleotide synthesis. Well- and moderately well differentiated adenocarcinomas induced with 1,2-dimethylhydrazine (DMH) are widely distributed throughout the colorectal tract with high TK activity, and the poorly differentiated type is mainly restricted in the proximal colon and the cecum with high TS activity in rats. Subcutaneously injecting the rats with SSM reduced TS activity in colonic nontumorous regions, but in the tumorous regions it reduced TK activity compared with that of the DMH-treated rats without SSM treatment. SSM is suggested to reduce the colorectal carcinogenesis induced with DMH by inhibiting DNA synthesis in a de novo pathway, and to suppress the development of the tumors by decreasing DNA synthesis in the salvage pathway in rats. 相似文献
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Devidze N.; Zhou Y.; Ho A.; Zhang Q.; Pfaff D. W.; Kreek M. J. 《Canadian Metallurgical Quarterly》2008,122(6):1248
Methadone is widely used in treatment of short-acting opiate addiction. The on-off effects of opioids have been documented to have profound differences from steady-state opioids. The authors hypothesize that opioids play important roles in either generalized arousal (GA) or aversive state of arousal during opioid withdrawal. Both male and female C57BL6 mice received steady-state methadone (SSM) through osmotic pumps at 10 or 20 mg/kg/day, and GA was measured in voluntary motor activity, sensory responsivity, and contextual fear conditioning. SSM did not have any effect on those GA behaviors in either sex. Females had higher activity and less fear conditioning than males. The effects of SSM on stress-responsive orexin gene expression in the lateral hypothalamus (LH) and medial hypothalamus (MH, including perifornical and dorsomedial areas) were measured after the behavioral tests. Females showed significantly lower basal LH (but not MH) orexin mRNA levels than males. A panel of GA stressors increased LH orexin mRNA levels in females only; these increases were blunted by SSM at 20 mg/kg. In summary, SSM had no effect on GA behaviors. In females, SSM blunted the GA stress-induced LH orexin gene expression. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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半固态铸造是一种新的材料成形技术,综述了半固态铸造合金的组织变化,坯料制备,充型过程数值模拟和应用等方面的研究成果,同时对我国发展半固态铸造技术得出了若干值得重视的问题。 相似文献