Y.P. Ma
,
J. Li
金属学报(英文版)
The corrosion resistance of pure magnesium with surface alloying layer obtained by a solid diffusion alloying technique has been analyzed. To establish the optimum treatment time, the experiments were performed at 480℃ for different solid diffusion time (8, 16, and 24h). The diffusion interaction effectiveness between Zn, Al mix powder and the sample surface, depending on the treatment time for diffusion at given temperatures, has an obvious influence on corrosion resistance and corrosion mechanism. Corrosion properties were studied using the constant immersion test (in 3.0% NaCl solution, temperature is (28±1)℃, and time is 96h). Optical microscopy (OM) and EDS (energy dispersive spectrum) composition analysis were used to examine the cross-sectional microstructural characteristics of alloyed layer of treated samples. It is shown that in comparison with the untreated samples, the treated ones possess a better corrosion resistance. The Al5Mg11Zn4 phase, which formed as a continuous phase due to the diffusion of Al, Zn, and Mg elements and subsequent interaction on the outermost layer of diffusion alloying zones (especially the samples treated for 24h at 480℃), was inert to the chloride solution compared with pure magnesium and acted as a corrosion barrier, and therefore the best corrosion resistance was obtained. This protective action of Al5Mg11Zn4 phase was found to change with its amount, which was controlled by the diffusion time at given temperature. It was concluded that the continuous Al5Mg11Zn4 phase (WP-zone) of the reacted layer in pure magnesium was beneficial from the point of view of corrosion resistance.
关键词:
Pure magnesium
,
null
,
null
Y.P. Ma
金属学报(英文版)
After three-body abrasion, the hardness re-distribution near the worn surface has aclose relationship with the carbon content of martensite steel. It is considered thatthere is a competition between the work-hardening and the temper softening, whichresults from deformation and friction heat of material. When the carbon content ofmartensite steel is below about 0.6%, the subsurface hardness distribution of materialis a softened layer sandwiched between two hardened layers, but above 0.6%C, nosoftened region appears on the hardness re-distribution curve.
关键词:
martensite
,
null
,
null
,
null
梁丽芸
,
吴爱苹
,
石大立
涂料工业
doi:10.3969/j.issn.0253-4312.2008.05.013
用半连续种子乳液聚合法制备了纳米级核/壳型聚(甲基丙烯酸甲酯-丙烯酸丁酯)[P(MA-BA)]乳液,保持水:单体:乳化剂:引发剂的质量比为60:40:1.5:0.3不变,考查了无丙烯酸存在下,反应温度、种子单体用量和壳层单体滴加速度等对核/壳型乳胶粒径的影响,结果表明适当提高反应温度、降低种子单体用量和降低壳层单体的滴加速度都可降低乳胶粒的粒径,当反应温度为85℃、种子单体占单体总量的10%和壳层单体滴加速度为0.23 mL/min时,可以获得粒径为74 nm,转化率为98.78%的P(MA-BA)乳液.
关键词:
核/壳乳液聚合
,
聚丙烯酸酯乳液
,
粒径
,
聚合工艺
周维
,
任殿福
,
王立军
,
陈怀满
,
于丽丽
,
韩兆让
高分子材料科学与工程
采用溶液聚合方式,合成了具有两亲性梳型结构的聚甲基丙烯酸十二酯-马来酸酐共聚物P（LMA-MA）。使用傅里叶变换红外光谱（FT-IR）、核磁共振（1H-NMR）等检测手段对聚合物的组成结构进行了表征。在选择性溶剂（水）中制备了P（LMA-MA）两亲性梳型聚合物的胶束,通过Zeta电位粒径分析仪和透射电子显微镜（TEM）探讨了两亲性梳型聚合物在胶束化过程中胶束形态和尺寸的影响因素。实验表明,由于两亲性梳型聚合物的结构特点,P（LMA-MA）形成200nm以上尺寸的胶束;在浓度范围0.5 g/L-1.75 g/L、温度范围25℃-50℃和pH值范围4-8时,胶束可稳定形成和存在。
关键词:
两亲性
,
梳型聚合物
,
合成
,
表征
,
胶束化
李佳
,
张忻
,
路清梅
,
张久兴
,
卫群
功能材料
机械合金化与放电等离子烧结技术(SPS)相结合制备了p型(Bi,Sb)2Te3合金块体.在300～423K的温度范围内测试了样品的电导率﹑Seebeck系数和热导率.系统研究了球磨时间对合金化与热电性能的影响.球磨2h的样品具有最低的热导率,因此其ZT值最高,在323K时为1.16,在373K达到最大值1.23.
关键词:
热电材料
,
机械合金化
,
放电等离子烧结(SPS)
李酽
,
汪信
,
岳明波
,
陆路德
,
朱俊武
材料导报
首次以天然红辉沸石水热合成了Y型、P型分子筛,以IR研究了水热合成体系中分子筛结构的演变及晶相分布规律.研究表明,在高H2O/Na2O、低Ca2+/Na+体系中,主晶相为Y型分子筛,在低H2O/Na2O、高Ca2+/Na+体系中,主晶相为P型分子筛.
关键词:
红辉沸石
,
水热合成
,
Y型分子筛
,
P型分子筛
,
红外光谱
于善青
,
田辉平
催化学报
doi:10.1016/S1872-2067(14)60149-2
以三甲基磷氧(TMPO)和三丁基磷氧(TBPO)为探针分子,用31P魔角旋转核磁共振(31P MAS NMR)法对稀土改性Y型分子筛的酸性进行了定性和定量分析。结果表明,以TMPO为探针分子的31P MAS NMR谱分别在δ=78,70,65,62,58,55和53处存在与酸中心相关的吸收峰,其中δ=78和70处吸收峰与分子筛内部和外部酸性有关,δ=65,62,58和53处吸收峰归属于TMPO在分子筛内部Br?nsted酸中心上的贡献,δ=55处吸收峰归属于TMPO在分子筛内部Lewis酸中心上的贡献。随着稀土含量的增加,中等强度Br?nsted酸中心(δ=62和58)数量显著增加,而强Br?nsted酸中心(δ=65)和较弱Lewis酸中心(δ=55)数量显著降低。结合分子筛骨架铝和非骨架铝对分子筛酸性的影响进一步探讨了稀土改型Y分子筛的酸性。
关键词:
Y型分子筛
,
稀土
,
酸性
,
31P核磁共振
郑翠红
,
ZHU Wei-Chang
,
王露
应用化学
doi:10.3969/j.issn.1000-0518.2008.08.026
采用共沉淀法合成了Y0.95Eu0.05(P1-xVx)O4(x:0,0.8)红色荧光粉.用X射线衍射、透射电子显微镜及真空紫外发射光谱测试技术对其相组成、粉体形貌和发光性能进行了表征.结果表明,制得的Y0.95Eu0.05(P1-xVx)O4(x:0,0.8)荧光粉的粒径约为300 nm,在147 nm真空紫外激发下,发射光谱的主峰位于619 nm;与Y0.95Eu0.05PO4荧光粉相比,Y0.95Eu0.05(P0.2V0.8)O4具有更好的色纯度,它的色度坐标更接近国际电视标准委员会(NTSC)规定的红色色度坐标(0.67,0.33),是具有很好应用前景的PDP红色荧光粉.
关键词:
Y0.95Eu0.05(P1-xVx)O4红色荧光粉
,
发射光谱
,
色度坐标
,
共沉淀
于志强
,
武高辉
,
姜龙涛
,
陈剑锋
复合材料学报
doi:10.3321/j.issn:1000-3851.2003.05.004
采用液相包裹法对Al2O3微粉进行稀土Y2O3表面改性,用挤压铸造法制备表面经稀土Y2O3改性的Al2O3P/6061Al复合材料,并对复合材料的显微组织及拉伸性能进行分析和研究.结果表明:表面经稀土Y2O3改性的Al2O3微粉能均匀的分布于基体中,界面润湿性得以改善,复合材料组织更加均匀.TEM观察表明:改性粉体在制备复合材料前后表面存在颗粒状包裹层.对其表面进行EDAX分析,结果显示含有Y,Al和O元素.粉体XRD图谱中有Y2O3衍射峰的存在.拉伸性能测试表明:改性粉体对Al合金增强效果明显增加,抗拉强度提高29.8%,屈服强度提高38.4%,延伸率提高10.3%.对拉伸断口进行SEM分析,改性后复合材料断口韧窝更加均匀、丰满,材料表现出良好的塑性.
关键词:
Al2O3微粉表面改性
,
铝基复合材料
,
微观组织
,
力学性能
,
稀土
刘虎生
冶金分析
doi:10.3969/j.issn.1000-7571.1999.01.011
采用HNO3和H2O2溶解试样,在8mol/LHNO3介质中,以溴酸钾将Ce(Ⅲ)氧化成Ce(Ⅳ),继以P204/CCl4萃取Ce(Ⅳ),将三价稀土元素与四价铈分离,用ICP-AES法测定CeO2标准物质中La,Pr,Nd,Sm,Gd和Y,分析结果均落在标准值的置信区间内,RSD<6%.
关键词:
CeO2标准物质
,
P204萃取剂
,
ICP-AES
,
稀土杂质元素
