Gr/Cu基SMA复合材料的阻尼行为

运用气压渗流法制备出了宏观石墨颗粒增强的形状记忆合金样品, 并利用多功能内耗仪对材料的阻尼行为进行了研究。发现在内耗-温度谱上有2个内耗峰, 分别出现在160 ℃和325 ℃左右。经分析后认为, 低温峰由孪晶细化引起, 高温峰则为马氏体相变峰。石墨颗粒加入后, 材料的相变内耗峰降低, 但背底内耗提高, 即材料的整体阻尼本领提高。根据测量结果, 对材料可能的阻尼机制进行了讨论。     

7050Al/Gr复合材料时效强化行为及内耗研究

采用力学性能和阻尼性能测试及透射电镜组织观察的方法, 研究了添加4%(体积分数)石墨(Gr)颗粒对7050铝合金组织、力学性能和阻尼性能的影响, 以及热处理对7050Al/4%Gr复合材料的组织、力学性能和阻尼性能的影响, 并对7050Al/4%Gr复合材料的内耗机理进行了初步探讨。结果表明: 在7050铝合金中加入4%Gr颗粒, 使其强度降低了约16%, 延伸率降低了37.5%; 热处理强化7050Al/4%Gr复合材料的力学性能变化趋势与7050铝合金的基本相同, 7050Al/4%Gr复合材料在120 ℃单级时效20 h后抗拉强度达到峰值521 MPa, 比7050铝合金有所降低, 但达到峰时效时间提前4 h; 7050Al/4%Gr复合材料的内耗值随着温度的升高而增加, 其除了材料本征阻尼以外, 在中、低温时的内耗主要是位错与第二相颗粒交互作用引起的位错内耗, 在高温下内耗主要由相界面、晶界、Gr与基体的界面微滑移引起。     

新型Fe-17Mn-5Cr-1.5Al/聚氨酯高阻尼复合材料制备及性能研究

采用胶结法制备Fe-17Mn-5Cr-1.5Al/聚氨酯高阻尼复合材料,成功实现了材料内部聚氨酯阻尼层的均匀可控分布以及与Fe-17Mn-5Cr-1.5Al合金层的紧密结合。采用多功能内耗仪测试了Fe-17Mn-5Cr-1.5Al/聚氨酯复合材料的内耗特性,发现其内耗峰随着测试频率的增加向高温方向移动,表现出典型的弛豫特性。研究了内耗峰高与阻尼层厚度、阻尼层层数之间的变化关系,发现当阻尼层厚度增加至2.0 mm时,或者阻尼层数增加至2层时,内耗峰高达到最大。相较而言,抗弯性能则随着阻尼层厚度和层数的增加而单调增加。Fe-17Mn-5Cr-1.5Al/聚氨酯复合材料的阻尼性能主要来源于聚氨酯阻尼层的贡献,而抗弯性能则主要来源于Fe-17Mn-5Cr-1.5Al合金层的贡献。     

Ti/Al复合粉末压坯低温烧结过程的内耗特征

为探究低温阶段Ti/Al之间的烧结机理,基于内耗测量技术系统研究了Ti/Al复合粉末压坯低温内耗行为。结果表明,Ti/Al粉末压坯的内耗性能具有明显的温度效应,升温测量过程中,270℃附近出现的不可逆内耗峰峰值随频率的增加而下降,随Al含量的增加而增加,该内耗峰是由应力释放引起的,是一个应力型内耗峰。降温过程中,230℃附近出现的内耗峰峰位随频率的增大向高温方向移动,具有一定的弛豫特征,该内耗峰源于Ti/Al复合粉末压坯升温过程由再结晶形成的Al晶界的滑移。     

Fe含量对等原子比NiTi形状记忆合金微观组织、相变行为和显微硬度的影响

采用光学显微镜、扫描电子显微镜、X射线衍射仪、差示扫描量热仪和显微硬度计等测试手段,研究了Fe含量对Ni_(50-x/2)Ti_(50-x/2)Fe_x(x=0.5%～3.5%)形状记忆合金微观组织、相变行为和显微硬度的影响规律.结果表明:NiTiFe三元形状记忆合金组织主要由Ni_(4.8)Ti_5Fe_(0.2)相、Ni_3Ti相和基体组成,随着Fe含量的增加,合金组织中等轴晶粒尺寸逐渐增大;合金的相变温度,随Fe含量的增加迅速下降;合金的显微硬度随Fe含量的增加而急剧增加,与Fe含量呈正相关关系,当x=3.5%时达到最大值469.91 HV.     

宏观石墨颗粒增强工业纯铝金属基复合材料位错阻尼机制的研究

运用空气加压渗流技术制备了宏观石墨颗粒增强的工业纯铝金属基复合材料, 在25～400 ℃温度范围和频率为0.5、1.0和3.0 Hz条件下在多功能内耗仪上测量了材料的内耗和相对动力学模量; 用透射电子显微镜对材料的微观结构进行了观察。依据内耗测量和微观分析研究了宏观石墨颗粒增强工业纯铝金属基复合材料的位错阻尼行为。结果表明, 在频率0.5～3.0 Hz范围内, 复合材料的阻尼与致密工业纯铝的阻尼相比较, 阻尼性能提高2～3倍。复合材料阻尼能力随着石墨颗粒体积分数的增加而增加, 但相对动力学模量在减小, 材料的位错阻尼是一种重要的阻尼机制。     

Gr/Al 复合材料的阻尼性能

通过内耗测量方法研究了石墨颗粒增强铝基复合材料(Gr/Al-MMCs)的阻尼性能, 并结合微观结构分析, 探讨了Gr/Al-MMCs产生高阻尼性的机制。内耗测量是在多功能内耗实验仪上进行的, 测量温度范围为25～400 ℃, 频率为1.0～3.0 Hz 。实验结果表明:含高体积分数石墨颗粒的Gr/Al-MMCs 是一种高阻尼材料, 其阻尼性能显著高于工业纯铝及石墨, 并且随石墨体积分数的增加而上升。经进一步分析认为, 由石墨颗粒引入的大量宏观缺陷和由残余热应力而导致的铝基体中的高密度位错是使Gr/Al-MMCs 具有高阻尼性能的主要机制。     

Cu-Al-Mn系低温形状记忆合金的微结构研究

研究Cu-Al-Mn系低温形状记忆合金的微观组织结构和马氏体相交温度Ms的关系。结果表明，合金的Ms点随烈和Mn含量增加而显著降低。通过合适的成分设计，得到了Ms约为110K的Cu-Al-Mn系形状记忆合金。     

超轻TiAl多孔材料的阻尼响应特征

在固相扩散反应和Kirkendall效应化学反应造孔基础上,引入可去除填充颗粒物理占位造孔,采用"均混—压制—脱溶—烧结"的四阶段工艺流程实现了孔隙率在40%~90%、孔径在微纳米至毫米量级、孔型和孔结构多样的TiAl多孔材料的制备。通过内耗测试考察了TiAl多孔材料的阻尼响应特征,实验发现,室温至600℃,材料阻尼与温度、应变振幅之间无明显依赖关系,但随测量频率的增加而增大,600℃以上,随温度升高阻尼迅速增大。此外,材料的阻尼随孔隙率的增大而增加,这种效应可通过孔周围的应力集中和模式转换机制来解释。     

Cu_(73)Al_(17)Mn_(10)形状记忆合金的显微组织和阻尼性能

研究热处理及变形对Cu73Al17Mn10形状记忆合金显微组织和阻尼性能的影响。结果表明,合金在铸态下主要为L21结构的β母相组织,经时效热处理后,转变为板条状马氏体。在室温下,该合金的低应变阻尼为弛豫型阻尼,高应变阻尼为静滞后型阻尼。均匀化退火后合金的内耗低于铸态。经轧制变形后,晶粒得到细化,有利于阻尼性能的提高。时效处理后,板条状马氏体变细,合金的阻尼性能得到进一步提高。     

Current situation and future trend of China rare earth luminescent material industry

<正>Rare earth luminescent material is one of the most important application sectors of rare earths.China enjoys the exceptional advantage to develop rare earth luminescent material for its abundant rare earth resources.After several decades'endeavor,China's rare earth luminescent material industry,headed by rare earth phosphor for lamp and LED and high efficient rare earth energy-saving light source,has been gradually developed into a scale industry.China has become a major production base of rare earth phosphor for lamps and rare earth     

China rare earth market review

正June 1~10,2014Rare earth market remained weak.Quoted price of rare earth products was similar to that in May.There was no sign of recovery in downstream market.The market of NdFeB magnetic materials and phosphor was depressed.Catalyst,polishing powder and ceramic industries remained inactive.Demand from downstream industry was soft.Consumers purchased on their needs.Suppliers had strong intention to sell.Prices of rare earth products     

Annual Report analysis of Chinese rare earth-related listed companies in 2013

<正>Chinese rare earth-related listed companies have published their 2013 annual reports.It can be understood from their reports that production and operation activities of Chinese rare earth-related companies were still heavily affected by macro economy and industrial policies.They basically followed the steps of national economy.In 2013,world economy recovered slowly but the economy     

Market opportunities and challenges for rare earth polishing powder

正1.Status of rare earth polishing powder Rare earth polishing powder with high content of cerium oxide began to replace iron oxide for glass polishing and became one of the key materials in glass polishing process since 1940.Compared with traditional iron oxide,rare earth polishing powder has many advantages,such as fast polishing rate,high polishing quality and long service life.It can achieve good surface quality and improve operation conditions.For example,in lens polishing,the polishing work that cerium     

Baotou Research Institute of Rare Earths developed a new RE alloy preparation technology

正Pyrometallurgy Laboratory of Baotou Research Institute of Rare Earths had independently developed a new preparation technology of rare earth alloy for NdFeB.The alloy can remarkably enhance the coercivity of NdFeB magnet but also evidently reduce the production cost of the magnet.The new master alloy was prepared in the kA pilot-scale electrolytic cell by the independent technology.The rare earth master alloy can be used as the raw material for NdFeB.Compared     

Market and recycling of NiMH battery

<正>Market status and future trend of NiMH battery1.Global market of small NiMH battery Global market size of small NiMH batteries declined year on year since 2011.The trend will continue to 2018,at the rate of 5%to 10%annually.Demand for small NiMH batteries will be stable gradually.Many electrical apparatuses are powered by the built-in lithium battery today,which is the main reason for the shrunk market of small NiMH batteries.But,for some products,small NiMH     

China rare earth market review

正September 1-10,2014 Affected by the National Day holiday,rare earth transaction was stagnant and the market showed a weak steady state.As there was no good news for downstream market,some products with flat demand would likely rally slightly for some time to     

2014 second batch of rare earth quota released

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矿用防爆轴流对旋主要通风机叶片ANSYS模态分析及应用

高效节能矿用防爆对旋主要通风机的叶片是主要通风机运行的关键部件,叶片在运行时不断受到气流的作用力,从而使叶片产生振动,当叶片振动的频率与叶片的固有频率接近时,容易产生共振从而导致叶片的断裂。一旦叶片断裂时,对主要通风机的安全运行产生致命的影响,从而导致矿山、化工等企业发生重大事故,将会产生不可估量的损失。基于有限元分析软件ANSYS,对高效节能矿用防爆轴流对旋主要通风机叶片进行模态分析及产生对应的六阶模态频率,对主要通风机叶片的运行频率、固有频率及产生的共振问题进行了原理分析,并且解决了叶片频率共振的问题,从而为主要通风机叶片结构设计提供理论依据,并对主要通风机叶片的安全运行提供保障。     

2013 NdFeB export analysis

<正>China totally exported nearly 24,000 tonsof NdFeB products during 201 3,including 18,825 tons of permanent magnet,valued USD 1.34 billion at an average price of 71.4 USD/kg;3,277 tons of NdFeB magnetic powder,valued USD 1 01 million at an average price of 30.9 USD/kg;1,334 tons of strip casting ribbon,with total export value of USD 74million at an average price of 55.3 USD/kg;and 586