氧化处理方法与多壁碳纳米管表面羧基含量的关系

从羧基定量化出发，采用红外光谱法、热重分析法和X-射线光电子能谱法详尽研究了氧化处理方法与多壁碳纳米管（MWCNTs）上引入羧基量的关系。结果表明，硝酸氧化法、混酸氧化法和混酸与过氧化氢共同氧化法均可以使MWCNTs表面产生羧基。热重分析法和XPS分析法可以定量分析MWCNTs表面羧基的含量，并且分析结果相近。XPS分析表明，2．5mol／L硝酸氧化48h可以使MWCNTs表面产生摩尔分数为4．80％的-COOH，而混酸（浓HNO3与浓H2SO4体积比为1：3）氧化4h可产生摩尔分数为5．35％的～COOH，如果进一步由质量分数20％的过氧化氢氧化2h，MWCNTs表面产生的-COOH摩尔分数提高到7．55％。     

T6热处理对1.0%CNTs@TiO2/2024复合材料腐蚀性能研究

目的 研究T6热处理对1.0％CNTs@TiO2/2024(CNTs质量分数为1.0％)微观组织和腐蚀性能的影响,以期提高2024复合材料的耐腐蚀性能.方法 通过熔铸法制备CNTs质量分数为1.0％的CNTs@TiO2/2024复合材料,并研究了T6热处理(495℃,2 h+180℃,4～16 h)对CNTs质量分数为1.0％的CNTs@TiO2/2024复合材料微观组织和腐蚀性能的影响.结果 经固溶处理(495℃,2 h),S相(Al2CuMg)和θ相(Al2Cu)基本融入基体中;在时效处理(180℃,12 h)后,S相和θ相均匀析出.当加入CNTs质量分数为1.0％的CNTs后,与2024合金相比,复合材料的腐蚀电流密度大幅度增加了77.4％.与2024合金相比,T6态复合材料的腐蚀电位增加了4.4％,腐蚀电流密度下降了80.9％.结论 CNTs的加入会降低2024合金耐腐蚀性能,但是合适的T6处理工艺能够很好地提升其耐腐蚀性能,有效拓宽该系复合材料的应用领域.     

肉桂精油-海藻酸钠可食性抗菌膜的研制

以海藻酸钠为成膜材料,并添加不同质量浓度的肉桂精油来制备可食性抗菌膜。根据膜的力学性能和抑菌性能,确定了可食性膜中添加海藻酸钠、甘油和肉桂精油的最佳质量分数,以及可食性抗菌膜的最佳干燥温度和干燥时间。实验结果表明：在海藻酸钠的质量浓度为20mg／mL,甘油的添加质量分数为1．0％,肉桂精油的添加质量分数为2．0％,干燥温度为50℃和干燥时间为4．5h的条件下,所制备的膜具有最佳的力学性能和抑菌性能。     

辐射防护用特种橡胶制品的制备与性能研究

一种新型γ射线防护用橡胶制品填充料由PbWO4和WO3复合制成，其组成为：WO3：PbWO4=40-60：60～40（质量分数）；制备方法：在分散剂、助剂存在下，由Na2WO4溶液与Pb（Ac）2溶液在快速搅拌下沉淀反应得到PbW04沉淀，然后将此PbW04沉淀加入到磨细的WO3浆体中，再研磨1～2h即成。该填充料与硫化橡胶乳液形成的分散系稳定性很好，制成的橡胶制品（手套）对59．5KeV的了射线的屏蔽率可迭15％～18％，抗拉强度达7．8～9．1MPa，断裂伸长率迭700～1000％；对产品中的Pb作迁移性检测，证明是符合安全卫生要求的。     

废纸纤维素/壳聚糖膜的制备及性能

为增强壳聚糖膜的力学性能,制备了废纸纤维素/壳聚糖膜.以包装废弃瓦楞纸为原料,通过碱处理和漂白处理得到再生纤维素,再以不同组分与壳聚糖制备成膜,并对不同原料膜进行形态观察和力学性能检测.研究结果表明:废纸纤维素呈丝状,纤维直径约为15～20μm,结晶度较原始瓦楞纸有大幅提高;当在质量分数为2％的壳聚糖溶液中添加相对质量分数为5％的废纸纤维素时,废纸纤维素/壳聚糖膜力学性能最好,最大拉伸强度达52.3 MPa,断裂伸长率超过20％,纤维素分布均匀.     

海藻酸钙水凝胶过滤膜的制备及其对硫酸钙的截留

以尿素为致孔剂制备了海藻酸钙(CA)水凝胶过滤膜,测试了其通量、截留率和力学性能;通过扫描电子显微镜(SEM)观测其过滤硫酸钙前后的表面形貌。结果表明,增加尿素含量,均导致膜应力和应变的下降;而膜的纯水通量则迅速增大,尿素含量为3.0%(质量分数)时达到28.7 L/(m2·h),为最大;0.2 MPa下,过滤1.7 g/L硫酸钙时对Ca2+和SO2-4的截留率分别为83%和92%,稳定通量达到21.7 L/(m2·h)。     

液体丁腈橡胶的化学改性及应用

用新型Rh-Ru双金属加氢催化剂研究液体丁腈橡胶(LNBR)加氢成液体氢化丁腈橡胶(LHNBR)的工艺。主要讨论LNBR胶液浓度、催化剂浓度、三苯膦用量、温度、压力和反应时间等因素对液体丁腈橡胶加氢的影响。得到较佳加氢工艺参数：NBR的质量分数为30％、催化剂质量分数为0．35％、三苯麟用量为催化荆用量的6～8倍、加氢温度140C、压力1．4MPa、反应时间6h,加氢度可达87％以上。获得的LHNBR用做氢化丁腈(HNBR)的增塑剂,可使HNBR具有好的耐油性和更高的耐热性能。因而LHNBR是一种新型、特种的耐热、耐油增塑剂。     

乳液基碳化硅纳米工作液的沉降稳定性、流变性与介电性

目前混粉电火花加工液添加的粉末粒径主要局限于微米级,与工作基液不能形成均匀、稳定的悬浮液.本研究以乳化液为基液,纳米碳化硅粉体(SiC)为分散相,十二烷基苯磺酸钠(SDBS)、羧甲基纤维素钠(CMC)等作分散剂,采用两步法制备了乳液基SiC纳米工作液,研究不同分散条件下SiC粉体在乳化液中的分散行为,分析了乳液基SiC纳米工作液的沉降稳定性、流变性和介电性.结果表明:质量分数为0.3％～0.6％的CMC对SiC纳米粒子的润湿、分散作用显著,而SDBS作用不明显;CMC分别与SDBS、SDS协同作用时,工作液均具有很好的沉降稳定性;当SDBS质量分数为0.3％,CMC为0.3％～0.6％时,工作液黏度呈非线性增加;当CMC质量分数为0.3％,SDBS为0.3％～1.4％时,工作液黏度先增大后快速降低;工作液电导率随CMC、SDBS分散剂质量分数的增加、液体温度的升高而增大.因此,当SiC质量分数为0.3％、添加0.3％～0.5％(质量分数)的CMC和0.3％～0.7％(质量分数)的SDBS,乳液基SiC纳米工作液有较好的沉降稳定性、流变性和介电性.     

镍锌铁氧体的制备及其吸波性能的研究

利用溶胶直接自蔓延反应制备了镍锌铁氧体纳米粉末，采用XRD分析了其结构。以聚乙烯醇为基体（PVA）制备了炭黑，镍锌铁氧体复合材料吸波平板；采用矢量网络分析仪测量了其在2～18GHz频带上的吸波性能。结果表明：具有双层结构的炭黑，镍锌铁氧体复合材料具有较好的吸波效果，试样厚度为3mm；当面层镍锌铁氧体的质量分数为40％，底层炭粉的质量分数为20％时，在8～18GHz的测试频段范围内，复合材料最大吸收峰值为-15．7GHz，优于-6dB的有效带宽为6．4GHz；当底层炭粉的质量分数为15％时，复合材料最大吸收峰值为-13．6GHz，优于-6dB的有效带宽为8．2GHz。     

铝粉对化学敏化水胶炸药性能影响的实验研究

为研究不同形状和含量的铝粉对化学敏化水胶炸药性能的影响,在水胶炸药中分别添加质量分数为1％、2％、3％、4％片状和粒状铝粉.对比分析添加不同的质量分数及不同形状铝粉水胶炸药的爆热、爆速和猛度变化情况.结果表明:随着铝粉质量分数从0％增加到4％,炸药的爆热增加,爆速和猛度下降.当炸药中分别添加质量分数为4％的片状铝粉和粒状铝粉的水胶炸药比不含铝粉的水胶炸药,其爆热分别提高了17.99％、16.54％,爆速分别降低了15.12％、13.27％,猛度分别下降了18.18％、16.78％.     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

From Industry 4.0 to Research 4.0. Development of High Performance Fibers in the Light of Digitization

We associate a variety of innovations with the term ＂Industry 4.0＂. The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Roman iron and steel: A review

ABSTRACT

The production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them.     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...