共查询到20条相似文献,搜索用时 140 毫秒
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《中国粉体技术》2021,(3)
通过定量混合3种粒度分布相对均匀的颗粒体系分样,得到粒径范围为20~110μm的多峰粒度分布标准物质。分样的粒度分布通过光学显微镜测量得到,量值溯源至He-Ne激光波长;标准物质的量值通过分样的粒径分布和混合比例计算得到。该标准物质已获国家市场监督管理总局批准为一级标准物质(编号为GBW12053),填补了我国在这方面的空白。利用研制的多峰粒度分布标准物质考察了国内主要厂家的激光粒度仪和国外品牌马尔文粒度仪的分辩率,发现不同厂家生产的粒度仪分辨率相差较大,同一厂家不同型号的激光粒度仪相差也较大。我国大部分厂家生产的激光粒度仪分辨率达到马尔文MS2000的分辨率,个别厂家的粒度仪接近或达到马尔文MS3000的分辨率。 相似文献
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黄河泥沙颗粒级配是研究水利工程及河床演变中泥沙问题的基本资料 ,黄河泥沙颗粒级配分析是一项重要的基础性研究工作。本文结合引进国际先进的激光粒度分析仪 ,开发应用于黄河泥沙颗粒分析工作的实际 ,研究解决了激光法测量泥沙级配资料换算到传统法测量泥沙级配资料的问题 ,探讨运用数学回归的方法 ,建立了回归数学公式 ,并对其合理性进行了检验分析 ,为保证黄河历史泥沙颗粒分析资料的连续性、完整性、一致性开展了探索性工作。 相似文献
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溶胶-凝胶法制备的光学薄膜具有优良的物理化学特性和广阔的应用前景.通过对整个化学法镀膜过程的分析,发现溶胶中胶体颗粒粒径的大小决定胶体颗粒之间的搭接,从而直接决定着所镀薄膜表面形貌和平整度.采用激光粒度仪对氧化锆溶胶的颗粒特性进行了为期28天的观测,发现氧化锆胶体平均粒径保持在10 nm左右,有逐渐增大的趋势,溶胶保存时间在20天以内较为适合镀膜.用原子力显微镜观测薄膜的表面相貌,所镀薄膜均匀,平整度小于5nm.可见采用激光粒度仪对溶胶颗粒粒径变化进行监控,能有效提高所镀薄膜的成膜特性,对溶胶镀膜的大规模生产和工艺成熟有一定的指导意义. 相似文献
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本文制备了四种不同粒度的超微粒AgBr照相乳剂,用X射线衍射技术对其粒子的大小进行了测定;观察到乳剂的紫外吸收峰随晶体颗粒的减小表现出逐渐蓝移;本文提出晶体表面的悬键的存在使得纳米晶体的平均键能升高,并对纳米AgBr乳剂的量子尺寸效应进行了解释。 相似文献
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借助于高温共聚焦显微镜(CLSM)、透射电镜(TEM)研究含Ti钢和无Ti钢的奥氏体晶粒长大行为。试样在1123~1473K之间保温60min时测量一系列温度下不同保温时间的奥氏体晶粒尺寸。结果表明:两种钢奥氏体晶粒尺寸随着温度的上升而增大;另外,两种钢奥氏体晶粒尺寸随时间的延长而长大,并符合抛物线方程。并且,观察到了第二相粒子,用第二相粒子的熟化公式和体积公式分别计算两种钢的含Ti粒子尺寸与体积分数。同时,采用修正的Gladman公式预测两种钢的奥氏体晶粒长大,实验结果和预测结果吻合较好。 相似文献
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Cijun Shuai Chongxian He Pei Feng Wang Guo Chengde Gao Ping Wu 《Virtual and Physical Prototyping》2018,13(2):59-69
Grain size and intermetallic phase were two key factors affecting the biodegradation behaviour of Mg alloys. In the paper, different grain size and intermetallic phase volume fraction were obtained by introducing Al into Mg–Zn alloy via selective laser melting. Results showed that the grain size refined while the intermetallic phase volume fraction increased with Al increasing. As Al was less than 3?wt.%, the grain refinement was the major factor affecting the degradation behaviour. The finer grain would create many grain boundaries, making the alloy passivate readily and resulted in a reduced degradation rate. However, with Al further increasing, the intermetallic phase became the main factor influencing the degradation behaviour though grain size was further refined. The large intermetallic phase volume fraction caused severe galvanic corrosion, accelerating the degradation. This work may provide guidance for balancing grain size and intermetallic phase on degradation behaviour of Mg alloys. 相似文献
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李培恩 《材料科学技术学报》1992,8(2):119-122
The available experimental results have beensummarized concerning the effect of grain size onminimum creep rate.There are two types of creeprate-grain size relations.One is that there is a criti-cal grain size above which creep rate is independentof grain size,below which creep rate increases withthe decrease of grain size.The other is that there isan intermediate grain size at which creep resistanceis optimum.The first relation usually occurs athigher temperatures(>0.5 T_m),and intermediatestress ranges,while the second relation at interme-diate temperature ranges(0.4-0.5 T_m)and higherstresses.For the two types of creep rate-grain sizerelations,the increase of the creep rates with the de-crease of grain size for small grain sizes is all due tograin boundary sliding.For large grain sizes,a dis-location climb mechanism is dominant in creepdeformation for the first relation,while aHall-Perch grain boundary strengthening effect isbelieved to play an important role by dislocationglide mechanism for the second relation. 相似文献
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R S Patil S S Suryavanshi S V Kakatkar A M Sankpal U R Ghodake S A Patil S R Sawant 《Bulletin of Materials Science》1994,17(2):111-119
XRD and microstructure studies were carried out on Ti4+ and Zr4+-substituted Li-Zn ferrites prepared by standard ceramic technique. All the ferrite compositions exhibit single phase formation.
The lattice parametera increases linearly with the content of Zn2+Zr4+ and Zn2+Ti4+, which is attributed to the ionic volumes of the cations involved. With substitution by Zr4+ the average size decreases, while with substitution by Ti4+ the grain size increases. In both the series grain size varies with the composition. Excess substitution of Zr4+ (x>0·4) leads to the formation of secondary images and discontinuous grain growth. Both Zr4+ and Ti4+ compositions obey Kurtz theory. 相似文献