Development and Application of WC-Based Alloys Bonded with Alternative Binder Phase

WC–Co alloys have enjoyed great practical significance owing to their excellent properties during the past decades. Despite the advantages, however, recently there have been concerns about the challenges associated with the use of Co, i.e. price instability (the major incentive for alternative binder development), toxicity and properties degeneration. Thus, the current study applies towards summarize the current knowledge of the impacts of different binders partial or total substitution of the traditional cobalt binder highlighting the influences of metal, intermetallic compound, ceramics (metal oxide) binders on the sintering behavior as well as mechanical properties of WC-based alloys, so as to provide reference for those who would like to enhance the performance of cemented carbides with better reliability advancing them to further wide applications and prepare the alloys in a way that is environment friendly, harmless to human health and low in production cost. It is concluded that the alternative for cobalt in tungsten carbide cemented carbide is economically and technically feasible. Strict control of the chemical composition of the binder coupled with taking into careful account the effects of sintering process and subsequent treatments is of great importance to improve the sintering behavior and tailor mechanical properties of tungsten carbide-based hardmetals.     

用磁控溅射和退火方法制备多层锗纳米晶

以Si为衬底,SiO2+Ge为复合靶,用超晶格方法(SiO2+Ge层和SiO2 + GeO2层交替生长)和磁控溅射技术制备镶嵌于Si/Ge氧化膜中的多层Ge纳米晶.X射线衍射(XRD)结果表明:退火样品中有Ge纳米晶生成.Ge纳米晶的声子限域效应引起Raman散射谱的Ge-Ge振动峰向低频移动.X射线光电子能谱(XPS)分析表明Ge主要以Ge0和Ge4+形式分别存在于所制备的超晶格中的SiO2+Ge层和SiO2+GeO2层中.透射电子显微镜(TEM)研究表明,Ge纳米晶被限制在SiO2+Ge层中且结晶性好.实验结果说明,相比于通常的单层介质膜方法,用该超晶格方法极大地提高了Ge纳米晶的密度,尺寸和空间分布的均匀性.     

纳微米PZT/水泥基压电复合材料的研究

采用溶胶-凝胶法合成了锆钛酸铅(PZT)纳微米粉体.XRD与SEM分析结果表明,经700 ℃煅烧的PZT粉体的平均晶粒尺寸约为26.4 nm,粉体团聚体的平均尺寸约为200 nm.采用干压成型-水化法制备了纳微米PZT/水泥基压电复合材料,研究了复合材料的压电及介电性能.SEM结果表明,PZT陶瓷相在基体中呈网状分布.PZT颗粒之间的良好连通性使复合材料具有优良的压电性能.     

历代洪州窑古瓷的元素组成特征的中子活化分析研究

对江西洪州窑从东汉晚期至晚唐五代8期400个瓷胎样品进行了中子活化分析, 分析结果显示碱金属元素Na和Rb、 碱土金属元素Ba及Fe等作为胎的助熔剂元素随年代的变化趋势相似, 都呈现出两头高中间低的U字形变化规律, 其中Fe作为呈色元素, 其含量的高低与瓷胎颜色的深浅是一致的. 分析结果还揭示洪州窑的发展与衰落以及窑址的不断变迁可能都与制瓷原料的发现与消耗有关. 对分析数据进行主成分分析, 可以将不同时期烧制的瓷胎样品大致分为5组: （1）东汉晚期东吴时期; （2）两晋和南朝时期; （3）隋代; （4）初唐和盛唐时期; （5）晚唐五代时期. 400 sherds were collected from Hongzhou Kiln covering 8 periods from Eastern Han to Late Tang Dynasty/the Five Dynastied and their bodies were analysed by NAA. The results show that the elemental contents in different samples are quite distinct, even for those in the same period. It means no single element can be used as “fingerprint” to distinguish the period. The curves of the contents of Na, Rb, Ba and Fe varying with time are very similar, like “U” shape. As a colorant element, the content of Fe is consistent with the color of the body. The higher content of Fe, the more dark of the body. The outcome of principal component analysis (PCA) indicate that most of the sherds can be classified into 5 groups: (1) Eastern Han & Eastern Wu; (2) Western Jin, Eastern Jin and Southern Dynasties; (3) Sui; (4) Early Tang and Middle Tang; (5) Late Tang & Five Dynasties.     

退火温度对镶嵌于SiO2膜中的Ge纳米晶结构的影响

采用磁控溅射及退火的方法制备了含Ge纳米晶的SiO2复合膜,应用拉曼散射和X射线衍射技术研究不同退火温度下的Ge纳米晶结构.结果表明:Ge纳米晶的结晶温度约为750 ℃.运用声子限域模型(RWL model)对样品的拉曼散射光谱进行拟合,确定出样品中Ge纳米晶的尺寸.通过XRD谱计算复合膜的内部压应力,得出由其引起的拉曼峰位的蓝移量,得出结论:压应力是造成拉曼模拟曲线与实验曲线峰位偏离的主要原因.     

铈对Zn-22%Al减振合金组织和力学性能的影响

借助于光学显微镜、透射电镜及扫描电镜,采用自然时效、人工时效等热处理工艺,研究了微量Ｃｅ对Ｚｎ－２２％Ａｌ减振合金显微组织和力学性能的影响,Ｃｅ具有细化Ｚｎ－２２％Ａｌ合金组织并障碍时效时晶粒长大和等轴程度降低的作用,在低于８０℃的温轧温度下效时,加Ｃｅ和不加Ｃｅ的Ｚｎ－２２％Ａｌ合金的强度不随时间的推移而变化。Ｃｅ还提高了Ｚｎ－２２％Ａｌ合金的强度和时效时力学性能的稳定性。     

微波激励ArS2体系机理的探讨

采用ab initio MP2/6-31+G方法计算了ArS2体系分析势能函数.并在此基础上,对Ar+S2的非反应动力学过程进行了研究.结果表明,Ar与S2的结合为很弱的物理吸附,其间没有化学键生成.在所计算的能量范围,Ar与S2的动力学过程主要是非弹性碰撞.通过对非弹性碰撞产物的分析,结果显示Ar原子对S2基态(X3Σ-g)有碰撞激发作用.     

Impact on the magnetic compressor due to CSR

When an electron bunch is compressed in a chicane compressor,the CSR (coherent synchrotron radiation) will induce energy redistribution along the bunch.Such energy redistribution will affect the longitudinal emittance as a direct consequence.It will also excite betatron oscillation due to the chromatic transfer functions,and hence a transverse emittance change.So,it is indispensable for us to find a way to alleviate the CSR-cansed emittance dilution and the bad result of chicane compressor in PKU-FEL.     

2-呋喃甲醛水杨酰腙及其三维镉(Ⅱ)配位聚合物的晶体结构和热稳定性

以2-呋喃甲醛水杨酰腙HL为配体与Cd(NO3)2·4H2O在乙醇和DMF的混合溶剂中反应,采用溶剂挥发法得到配位聚合物[CdL2]n.通过FT-IR、热分析和X-射线单晶衍射等手段对其进行表征.结构表征表明配体2-呋喃甲醛水杨酰腙HL属于单斜晶系,空间群为P2(1)/n,晶胞参数为n=0.49864(9) nm,b=2.0673(4) nm,c=1.0694(2) nm;β=101.394(3)°,V=1.0806 (4) nm3,Z=4.配位聚合物[CdL2]n属于四方晶系,空间群为P41212,晶胞参数为a=0.9710(3) nm,b =0.9710(3) nm,c =2.3162(11) nm,α=β=γ=90°,V=2.1838(14) nm3,Z=1.热重分析表明,该配位聚合物具有很高的热稳定性.     

2-呋喃甲醛水杨酰腙铜配合物的合成、晶体结构及抑菌活性

以2-呋喃甲醛缩水杨酰腙(HL)为配体,将HL与CuCl2·2H2O在乙醇-丙酮体系中反应得配合物CuL2,采用X-射线单晶衍射、X-粉末衍射、元素分析和红外光谱等手段对其进行表征.结构分析表明配合物CuL2呈现平面四方构型,属于单斜晶系,空间群P2(1)/n,晶胞参数a =0.6034(6) nm,b=1.5894(15) nm,c=1.2164(12) nm,β=101.576(18)°,V=1.1428(19) nm3,Z=2.热重分析表明,该配合物具有较好的热稳定性.用琼脂扩散法测定了CuL2对大肠杆菌、金黄色葡萄球菌和绿脓杆菌的抑制活性,结果显示CuL2对大肠杆菌和金色葡萄球菌有显著的抑制作用.