铌对(Y,Nb)掺杂的二氧化钛压敏-电容性能的影响

研究了铌对(Y,Nb)掺杂的二氧化钛压敏-电容性能的影响.研究中发现掺入0.10mol%Nb2O5的样品显示出最低的视在电场(EB=8.8V/mm)、最高的非线性常数(α=7.0)以及最高的相对介电常数(εr=7.6×104),与样品的晶界缺陷势垒特性、电容和电阻的频谱特性相一致.样品的性能变化可用Nb5+对Ti4+的掺杂取代和该取代存在的饱和值来解释.     

低温单斜相BiPO_4∶Tb~(3+)纳米晶的合成及其发光性能

以无水乙醇为反应溶液,采用室温共沉淀制备了低温单斜相BiPO4∶Tb3+绿色荧光纳米材料,并进行高温烧结处理。利用X-射线衍射(XRD)、透射电镜(TEM)和荧光光谱分别对所得样品的相结构、形貌以及发光性能进行研究。结果表明:通过高温烧结,样品没有发生晶型转变,仍然保持单斜相结构和纳米颗粒形貌。同时,Tb3+离子作为绿色发光中心进入到BiPO4的晶格中取代Bi 3+的格位,在370nm激发下,观察到Tb3+离子的特征跃迁(5D4→7FJ,J=6~3),其中以5D4→7F5跃迁发射(543nm)为主;并考察了BiPO4∶Tb3+纳米晶发光强度随Tb3+掺杂量的变化关系,发现其淬灭浓度高达20mol%。     

添加剂对Y2Ti2O7陶瓷的微波介电性能的影响（英文）

研究了CrO3、Nb2O5、SiO2及Al2O3对Y2Ti2O7陶瓷的烧结性能、相组成和微波介电性能的影响.其中Nb2O5掺杂能够降低Y2Ti2O7陶瓷材料的烧结温度,提高基体陶瓷的介电常数和品质因子,引起谐振频率温度系数的明显变化.且随着Nb2O5含量的增多,所有样品的主晶相仍为立方烧绿石型Y2Ti2O7,Nb5+可能进入烧绿石结构中,部分取代Ti4+所在位置.实验结果表明:1mol%Nb2O5掺杂的陶瓷材料在1420℃下烧结致密,具有最佳的微波介电性能:εr=61.8,Q×f=9096GHz(f=5.494GHz),τf=54×10-6/℃.     

稀土掺杂双钙钛矿结构红色荧光粉的制备及其发光性能

采用高温固相反应法制备了Sr_(2-x)BaxMgMoO_6∶Eu~(3+)(x=0~1)双钙钛矿结构红色荧光粉。探讨了预处理及煅烧制度、Ba取代量对Sr_(2-x)BaxMgMoO_6∶Eu~(3+)荧光粉的相结构和发光性能的影响。Sr_2Mg_(0.94)Eu_(0.06)MoO_6荧光粉最佳制备工艺为:在700℃下预处理1h再升温至1050℃预处理1h并随炉降温后研细,再在1300℃煅烧4h,所得样品主相为双钙钛矿结构的Sr2MgMoO6四方相。其最强发光峰位于617nm附近,对应于Eu3+的5D0→7F2电偶极跃迁。随着Ba2+对Sr2+的取代量的增加晶体对称性提高,晶体结构由四方相变为立方相,样品的激发峰强度显著提高。由于晶体对称性的提高,抑制了荧光粉在617nm处5D0→7F2红光发射,其发光由电偶极跃迁占主导转变为磁偶极跃迁占主导。     

利用碱金属碳酸盐提高空气中制备BaMgSiO_4∶Eu~(2+)的发光性能研究

通过高温固相反应在空气中制备了一系列Eu2+掺杂的BaMgSiO4∶Eu2+发光材料,研究了其发光性能及M2CO3(M=Li、Na、K)助溶剂对其性能的影响。利用X射线粉末衍射(XRD)、荧光光谱(PL)和扫描电镜(SEM)对合成的样品进行表征。研究表明,Eu2+进入Ba(1)和Ba(2)位置有利于Eu2+在空气中稳定存在。M2CO3(M=Li、Na、K)助溶剂促进Eu3+离子在空气中还原成Eu2+离子,提高了BaMgSiO4∶Eu2+的发光强度。当Na2CO3用量为6%时,BaMg-SiO4∶Eu2+的发光强度达到还原气氛中制备的91%。     

颜色可调Y(PO3)3:Tb3+,Yb3+上转换发光材料的共沉淀制备及性能

采用共沉淀法制备Tb3+,Yb3+共掺杂Y(PO3)3上转换发光材料,通过X射线粉末衍射仪(XRD)、扫描电镜(SEM)、傅里叶红外光谱(FT-IR)和上转换荧光光谱仪(UPL)对制备产物的结构和性能进行表征分析.结果表明,所制备样品属于单斜晶系空间群为P21/c的Tb3+和Yb3+共掺杂Y(PO3)3晶体.在近红外光的激发下,所制备Y(PO3)3:x Tb3+,20％(摩尔分数,下同)Yb3+样品发射出Tb3+特征的蓝绿色光.Tb3+掺杂量直接影响着制备产物的上转换发光性能,当Tb3+掺杂量为2％ ～10％时,Tb3+的5 D4→7 F6发射峰分裂为481 nm和491 nm两个发射峰;当掺杂量为5％～20％时,位于547 nm处绿光发射为最强发射峰;当Tb3+掺杂量高于20％时观察到浓度猝灭现象.Tb3+/Yb3+的掺杂量比例和近红外光激发功率密度对所制备样品的上转换发光性能也有明显影响.适当调节样品中Tb3+/Yb3+掺杂比例可实现对制备的Y(PO3)3:x Tb3+,20％Yb3+样品的上转换发射蓝绿光颜色的调控.对Y(PO3)3:Tb3+,Yb3+样品的上转换发光机理进行探索,其中属于Tb3+特征的5 D3→7 FJ(J=6,5,4)和5 D4→7 FJ(J=6,5,4,3)跃迁带发射分别属于三光子吸收和双光子吸收机制.     

Nb2O5掺杂对TiO2陶瓷性能的影响

在Nb2O5含量x为0.1～1.5%的范围内,研究了Nb2O5掺杂对TiO2压敏陶瓷电性能的影响.发现x＝0.7%的样品显示出最低的压敏电压(Eb=8.57V/mm )以及最高的相对介电常数2.385×104.分析认为Nb2O5掺杂的实质是Nb5 固溶于 TiO2中取代Ti4 使晶粒半导化,但掺杂量受晶格畸变作用有一定限制.     

Zn2+/Co2+比变化对Co-Al-Zn-O系晶体结构和色度的影响

以CoAl2O4组成为基础,以Zn2+逐步取代Co2+,考察其组成变化对晶体结构和色度的影响.研究表明,随着Zn2+的量增加,Co1 -xZnxAl2O4晶体的晶胞参数a值逐渐改变,当X=0.5时a值开始下降;另外,当Zn2+/Co2+比值＜1时,样品中以CoAl2O4尖晶石为主要物相,当Zn2+/Co2+比值≥1时,样品则以ZnAl2O4尖晶石为主要物相.且样品的蓝度在Zn2+/Co2+比值=1时处于最小值.     

半导体陶瓷致冷材料的性能与结构

采用新的陶瓷工艺技术,在气氛保护条件下,通过固相烧结反应法制备出温差电多晶材料。对膺三元固溶体化合物 P 型(72%Sb_2Te_3+25%Bi_2Te_3+3%Sb_2Se_3)和 N 型(90%Bi_2Te_3+5%Sb_2Te_3+5%Sb_2Se_3)的掺杂陶瓷样品进行了性能与结构研究。找到了最佳工艺制度。样品性能参数为:N 型:α=186μV/K σ=1250Ω~(-1)·cm~(-1) λ=14.7mW/(cm.K) Z=2.9×10~(-3)/KP 型:α=220μV/K σ=900 Ω~(-1)·cm~(-1) λ=14.0mW/(cm.K) Z=3.1×10~(-3)/K     

TiO2纳滤膜对重金属离子的截留性能

采用孔径为1.5 nm的TiO2纳滤膜,在压力0.4～0.8 MPa,pH值3～7的条件下,考察了膜对浓度范围为50～500 mg/L的Cu(NO3)2、Ni(NO3)2、ZnC12和CdC12四种单组份重金属溶液的截留性能.结果表明:除Cd2+外,膜对重金属离子的截留率随溶液浓度的增大先增大,当浓度达到200 mg/L后趋于稳定;升高压力膜的离子截留率会略有增加;当pH=6时,膜对Ni2+和Cd2+的截留率最低,而对Cu2+和Zn2+的截留率在pH=5～6时达到最高.TiO2膜对Cu2+、Ni2+、Zn2+和Cd2+的最高截留率分别可以达到96.9％、95.9％、92.5％和83.2％.     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

Certification Becomes Important for the I Quality; and Safety Supervision of the Chinese Liquor Sector

The end of 2007, over 200 unit products of more than 80 Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits, beer, wine, yellow wine, fruit syrup wine and others, and cover over 80% of the national top-branded liquor products.……     

Deposition and Coating Properties on CVD Tungsten

Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster.     

Analysis of marine hydrobiont lipid extracts as possible cryoprotective agents

We studied a combined effect of the cryoprotectants both of lipid and carbohydrate origin at the presence of DMSO or without it on cell viability and the RNA synthesis in the embryonic mollusc and echinoderm cell cultures obtained at different developmental stages. Cryoprotective properties of exogenous lipids correlated with their thermotropic behavior. Lipid extracts from marine hydrobiontes, which thermal transitions are characterized by relatively small part of calorimetric thermogram area lying at temperatures above 0 °C (6–18%), were found to possess a considerable cryoprotective activity. The results are discussed in relation to the prediction of the cryoprotective activity of lipid extracts for marine animal cells. In addition, it was found that marine invertebrate cells can be cryopreserved without DMSO at the presence of trehalose and lipid extracts of some marine hydrobiontes.     

Low-Temperature Properties of Silver

Pure silver is used extensively in the preparation of high-temperature superconductor wires, tapes, films, and other configurations in which the silver not only shields the superconducting material from the surrounding materials, but also provides a degree of flexibility and strain relief, as well as stabilization and low-resistance electrical contact. Silver is relatively expensive, but at this stage of superconductor development, its unique combination of properties seems to offer the only reasonable means of achieving usable lengths of conductor. In this role, the low-temperature physical (electrical, thermal, magnetic, optical) and mechanical properties of the silver all become important. Here we present a collection of properties data extracted from the cryogenic literature and, to the extent possible, selected for reliability.     

Early ironwork in Biscay: Survey,excavation, experimentation and materials characterization. An integral study of the mountainside ironworks (ferrerías de monte or “haizeolak”)

ABSTRACT

The production of iron in Biscay (Basque Country, Spain) has been a hallmark of this territory of the North of the Iberian Peninsula throughout its history. The Archaeology team of the Basque Country Mining Museum has spent 13 years, so far, studying the origins of this activity through the evidences left at the old pre-hydraulic iron production workshops known as mountainside ironworks (ferrerías de monte) or haizeolak. It has catalogued 170 archaeometallurgical sites of this type in Biscay, and the archeological excavation of some of them has led to the knowledge of the different stages of the production process that took place in these workshops. The team has also experimentally reproduced the work carried out in a mountainside ironworks from the High Middle Ages, and it has currently started the characterization process of this type of activity through the study of the collected materials.     

Mechanism Study on the Wear of CrAlTiN Coated High-Speed Steel Twist Drills Under Dry Cutting Conditions

As demands about environment protection are growing up, dry cutting technology is getting more and more concerns from all over the world. Main works performed here are study on dry cutting performances and wear mechanisms of M2high-speed steel (HSS) twist drills with CrAlTiN multicomponent coatings, which was deposited using magnetron sputter ion plating system, in drilling 45 and 30CrMnSiA steel, and their comparisons to those in drilling the same steel but using monolayer CrN and commercial TiN coated drills. Drilling performances of drills are evaluated mainly through the measurements of width on outer corner flank land and the cutting forces. Results show that performances of CrAlTiN coated drills are better than those of monolayer CrN and TiN coated drills. In drilling 45 and 30CrMnSiA steel, the average tool life of the CrAlTiN coated drills are 17.2 and 11.8 times higher than those of the uncoated drills. Observing wear of the drill with scanning electronic microscope, results show that there is no crack or spallation of the CrAlTiN coatings in wear zones. Main mechanism of the wear here is adhesion.     

Study on Bond Ability of Arc-Spraying Coatings with Different Surface Pretreatment on Cast-Iron

Arc spraying coatings are widely used in various applications, but uncommon in cast iron substrate. Different surface pretreatment technology is tested on substrates of gray cast iron. Surface roughness and residual stress were measured by TR200 and X-ray diffraction analyzer. Influence of different surface pretreatment methods ( dry blasting and fusebond) on roughness and residual stress was analyzed. The arc-sprayed coatings of wire 3Cr13 (φ2mm) on gray cast iron substrate is studied. The microstructure and interface of bonding layer were observed by SEM. The bond strength was taken by tensile test. Results show that bond strength with grit blasting is higher than fuse-bond; it is feasible to make wire 3Cr13 coating with arc spraying on cast iron substrate roughened by grit blasting.     

Structural Characteristics of TiO2 Ceramic Coating by Micro-Plasma Oxidation

TiO2 ceramic coatings with thickness of 20 μm were formed on the surface of pure titanium by micro-plasma oxidation. Their micro-structures were investigated by by using X-ray diffraction and their surface images were detected by using scan electronic microscope. There were three kinds of TiO2 coatings, pure anatase type TiO2 phase, mixed phases consisted of rutile type TiO2 phase and anatase type TiO2 phase, pure rutile type TiO2 phase. The coating surface with the pure anatase type TiO2 phase is rough, while the coating surface with the pure rutile type TiO2phase is smooth. The upper coating surface with the mixed type TiO2 phases is anatase type TiO2 structure and the subsurface of the TiO2 coating is rutile type TiO2structure.     

Evaluation of fatigue life of steel using steel grain size

The insightful discussion of the relationship between the construction of metallographic and fatigue life and proposition of mathematical relationships describing this relationship was conducted in the paper. This paper presents a method for estimating the fatigue life, based on the construction of the microstructural material taking into account the grain size and the participation of ferrite and pearlite phase.