纳米TiN粉分散工艺优化研究

运用超声分散技术研究了纳米 Ti N粉的分散性能 ,得到了优化的超声及分散工艺参数。实验结果表明 ,分散体系中表面活性剂的引入是必要的 ,表面活性剂的加入量要合适 ;非离子型表面活性剂的分散效果优于阴离子型表面活性剂 ;适当的超声时间及频率可以改善纳米 Ti N粉体系的分散状况。分散体系的 p H值对分散状况有一定的影响。     

硅油基磁流体中磁微粒分散体系形成的条件及其影响因素的研究

硅油基磁流体由于具有良好的耐热性能已引起人们的关注，但与硅油相溶的表面活性剂较少，如何将磁微粒高度地分散在硅油中，是制备硅油基磁流体的关键。本文探讨了以化学共沉淀法制备的纳米Fe3O4微粒在硅油中高度分散体系形成的条件及其影响因素。提出了使磁微粒稳定地分散在硅油中的方法。     

超细氧化铝浆料流变性及稳定性能研究

以超细氧化铝粉体为原料,加入粘结剂等分散在溶剂中形成浆料,并对它们的流变性能和分散稳定性做了测试和比较。利用RS600型转矩流变仪测试不同条件下超细氧化铝浆料的流变性能;利用Turbiscan Lab浓缩体系分散稳定性分析仪测试超细氧化铝浆料的动态稳定性。结果表明,随着超细氧化铝浆料浓度的不断增加,浆料由不稳定到稳定,最终可达到无任何流动性的膏状。随着黏结剂含量的提高,浆料的黏度变大,在低剪切下表现出较高的黏度,有利于防止沉降,提高浆料的稳定性。触变性测试结果还表明,只有当加入适量的添加剂,才能够使得浆料中的颗粒形成均匀稳定的分散结构。对超细氧化铝浆料流变性能和分散性能的研究,综合考虑浆料的黏度、流动性和分散稳定性,为超细氧化铝浆料的配料、输送设备的设计及其下游产品涂覆等应用提供重要参考。     

Ni-SiC复合镀层的耐蚀性及其电化学机理研究

通过测量动电位极化曲线、电化学阻抗谱（EIS），并结合SEM进行Ni-SiC复合镀层的耐蚀性及其电化学机理的研究。结果表明，三类镀层在两种体系中呈现了不同的腐蚀规律，在3．5％NaCI体系中，纯镍镀层的耐腐蚀能力强于复合镀层：而在强氧化性介质中腐蚀规律发生了很大的变化，复合镀层的耐蚀性又高于纯镍镀层。SiC粉体在镀层中引入的大量的错综复杂的网状结构，造成表界面的电荷转移电阻Rt和蚀孔电阻RL大幅增加，有效分散了腐蚀极化电流，阻碍了腐蚀的发生和发展。     

纳米晶镁铝水滑石／聚乙烯复合阻燃料的制备

采用共混法制备聚乙烯／镁铝水滑石纳米复合材料。XRD、SEM、TEM和性能测试表明：镁铝水滑石纳米晶体分散在聚乙烯基体中，且有少部分发生插层；阴离子表面活性剂对水滑石的处理效果要优于偶联剂；pH值对处理效果有一定影响；镁铝水滑石阻燃剂填充聚乙烯体系阻燃效果，要优于填充A1（OH）3阻燃剂。     

金刚石超细粉体粒度测试中分散条件的探索

粒度的准确测定关系到金刚石性能的表征。本文研究了试样浓度、超声波强度、分散时间及分散剂的加入对金刚石微粉粒度测定结果的影响，结果表明，试样浓度低或高，粒度测定结果偏大；超声波强度的增大和超声波分散时间的延长明显地有利于粒子的分散，有利于粒度的准确测定；加入适量的分散剂六偏磷酸钠后，测试结果重现性好。     

利用叶轮搅拌与超声振动制备Al—Pb合金轴瓦

利用叶轮搅拌与超声振动， 分散和乳化ＡｌＰｂ 熔体， 通过铸造方式制备合金轴瓦。研究表明， 叶轮搅拌时， 存在熔体分散的临界搅拌速度， 并随Ｐｂ 含量的增加临界搅拌速度提高； 对搅拌液的超声乳化与声空化有关， 分散效果受超声参数及工艺条件的影响。文中从Ｐｂ 聚并与分散的传质过程， 探讨了叶轮搅拌与超声振动的作用制机及其装置的设计方法， 优化了铸造工艺过程。     

纳米TiO2颗粒的分散

研究了分散剂对于纳米TiO2颗粒在正丁醇中分散效果的影响，分别加入分散剂三乙醇胺、SDBS，吐温．80，乳化剂OP-10等来改善其分散性，通过稀悬浮液的吸光度、平均粒径、Zeta电位来表征分散效果的好坏，吸光度越大，平均粒径越小，Zeta电位越大，则分散稳定性越好。结果表明：在5ml正丁醇中加入1mgTiO2，再分别加入各种分散剂，当三乙醇胺（TEA）的质量分数为1．4％时，SDBS的质量分数为0．8％时，吐温．80的质量分数为0．8％，乳化剂OP-10的质量分数为0．6％时，分别对应的分散体系有较好的分散稳定性。     

分散剂涂覆处理对碳纤维在油性基体中分散性能的影响

目的获取效果较好的碳纤维在油性基体中的分散处理方法。方法采用IW,SCAT,MLBH(脂肪醇醚磷酸酯盐)和TEDPS四种分散剂对碳纤维进行涂覆处理,之后于溶剂油D80中分散,以表面电荷量和浊度值对其分散性进行评价,并分析分散剂浓度、分散剂类型、碳纤维长度、分散体系碳纤维浓度对分散效果的影响。对最佳条件下分散前后的碳纤维进行表面形貌结构与化学组成的对比表征。结果采用四种分散剂对碳纤维表面进行涂覆处理,均能有效改善碳纤维在油性材料中的分散性,其中以油溶性离子型表面活性剂MLBH的处理效果最好。分散剂浓度存在一最佳值;碳纤维越长,越不利于分散;分散体系碳纤维浓度越低,越有利于分散。结论 MLBH最佳浸丝浓度为0.3%(质量分数)。考虑到工业应用需求,浸丝后的碳纤维以长度10 mm、质量浓度50 mg/L进行分散时,分散效果最好。     

偶联剂在涂料中的作用机理及其应用

本文简述了偶联剂在涂料中提高附着力及润湿分散的作用机理，并介绍了偶联剂在几种不同涂料体系中的应用。     

Electroless deposition and investigation of composite coatings based on nickel or cobalt matrix,including boron nitrides as dispersoids,on polyethylene terephthalate substrate

Composite coatings, based on nickel or cobalt matrix with incorporated boron nitride particles (BN) as dispersoid, have been chemically deposited and investigated. The mass, and relative thicknesses, of the obtained composite coatings, as well as the number of co-deposited particles, depending on the type (alpha boron nitride – BN(h) or cubic boron nitride – BN(c)) and particle size of the dispersoid, as a function of dispersoid concentration in the working electrolyte and the concentration of the reducing agent in the plating electrolyte have been determined. The morphology, structure and chemical composition of the deposited coatings have been characterised by means of SEM and EDS analysis.     

Formation of surface layer based on Al3Ti on aluminum by laser cladding and its compatibility with ceramics

Intermetallic compound Al₃Ti or intermetallic compound matrix composite (IMC) surface layers were formed on Al surface by laser cladding. To form sound IMC surface layers, laser conditions must be controlled to suppress the melting of base metal. With increasing the volume fraction of ceramics in the IMC layer, it needed higher laser power to obtain IMC layer although the control of laser conditions became easier. During laser cladding, TiB₂ melted by laser irradiation and then homogeneously precipitated as fine particles at a cooling stage. On the contrary, TiC and SiC hardly melted and were dispersed in Al₃Ti matrix. SiC reacted with Ti to form titanium-silicide or TiC, which made the composition of matrix richer in Al than Al₃Ti and caused degradation of the wear property. IMC surface layer improved the wear property of Al substrate. The particle size as well as volume fraction of dispersoid ceramics affected the wear property.     

金刚石微粉粒度不同检测方法的比较与研究

本文分析比较了不同型号激光粒度分析仪测量同一金刚石样品结果的差异。同时还比较了激光粒度仪与沉降管法对同一样品检测结果的差异。实验发现，由于不同型号的激光粒度分析仪设计原理、数据采集方式、算法不同，导致检测结果有所差别；另外，不同方法检测结果没有可比性。因此使用激光粒度分析仪检测粉状物料时，应注明所使用的仪器型号。该结论对超硬材料和磨料磨具行业微粉粒度组成检测有重要的参考价值。     

Dispersoid Formation and Stability in Alloys

Analysis of dispersoid formation and stability indicates that in-situ formation of an adequate volume fraction of fine particles can be thermodynamically incompatible with stability against high-temperature coarsening. The theory of particle coarsening is extended to include the effects of grain boundaries and dislocations. Theoretical analysis predicts that particle dragging by migrating grain boundaries combined with enhanced coarsening by grain boundary diffusion can give denuded regions near grain boundaries. These predictions of enhanced coarsening and particle dragging are in accord with experimental observations on α-Ti and Ti₃Al based alloys.     

A theoretical concept for the design of high-temperature materials by dual-scale particle strengthening

The creep behavior of dual scale particle strengthened (DSPS) metals containing particles of two different size scales, namely nanometer size dispersoids and reinforcements with typical dimensions in the micrometer to millimeter range, is analyzed theoretically. Based on the concept of thermally activated dislocation detachment from dispersoid particles as rate-controlling mechanism in dispersion hardened matrices, a new creep equation for this advanced material class is developed. Analysis of the model leads to the prediction that creep strength levels far superior to today's best dispersion or reinforcement strengthened high temperature materials can be achieved by using dispersion and reinforcement hardening in combination and following certain design guidelines, related to the selected particle parameters. In particular, it is shown that a volume fraction mix of about 3/4 reinforcements with about 1/4 dispersoids is ideal in many cases provided reinforcements with sufficient aspect ratio and size are selected.     

Chemical deposition of metal composite coatings on plastics

Recently interest in electroless deposition of metal dispersion coatings on plastics has increased. These coatings are obtained through incorporation of solid dispersoids in the deposited metal matrix. Thin coatings with incorporated nanoscaled particles have gained a special interest with a view to their application in microtechniques.

The present review summarises the data available in the literature concerning chemically deposited nickel-phosphorus and copper dispersion coatings on ABS polymers from alkaline electrolytes. The studied dispersoids are SiC and Polyamide (PA) with particle size of 1 μm and TiO₂ and SiO₂ with particle sizes in the nanoscale range. The effects of the nature and size of dispersoid particles and their concentration in the base electrolyte, as well as the influence of electrolyte components and experimental conditions on the process kinetics, on the structure of dispersion coatings produced and on the degree of incorporation of dispersoids in both metal matrices have been established.     

Numerical simulation of powder effect on solidification in directed energy deposition additive manufacturing

An integrated simulation of powder effects on particle temperature and microstructural evolution in laser directed energy deposition additive manufacturing process was carried out. The spatial distribution of the flying powder particles was simulated by the discrete element method to calculate the energy for the flying powder particles under the laser–particle interaction with electromagnetic wave analysis. Combined with the phase field method, the influence of particle size on the microstructural evolution was studied. The microstructural evolution is validated through comparison with experimental observation. Results indicate that the narrow particle size distribution is beneficial to obtaining a more uniform temperature distribution on the deposited layers and forming smaller equiaxed grains near the side surfaces of the sample. Appropriate powder particle size is beneficial to the conversion of the electromagnetic energy into heat. Particles with small size are recommended to form equiaxed grains and to improve product quality. Appropriate powder flow rate improves the laser energy efficiency, and higher powder flow rate leads to more uniform equiaxed grains on both sides of the cross-section.     

A new model for prediction of dispersoid precipitation in aluminium alloys containing zirconium and scandium

A model has been developed to predict precipitation of ternary Al₃(Sc, Zr) dispersoids in aluminium alloys containing zirconium and scandium. The model is based on the classical numerical method of Kampmann and Wagner, extended to predict precipitation of a ternary phase. The model has been applied to the precipitation of dispersoids in scandium containing AA7050. The dispersoid precipitation kinetics and number density are predicted to be sensitive to the scandium concentration, whilst the dispersoid radius is not. The dispersoids are predicted to enrich in zirconium during precipitation. Coarsening has been investigated in detail and it has been predicted that a steady-state size distribution is only reached once coarsening is well advanced. The addition of scandium is predicted to eliminate the dispersoid free zones observed in scandium free 7050, greatly increasing recrystallization resistance.     

原位生成TiC对快速凝固Al-8Fe合金显微组织的影响

通过对不同TiC粒子含量的快速凝固Al-8Fe合金条带显微组织的观察发展：随着TiC含量的增加，合金的显微组织产生明显的细化，使快凝合金条带的耐浸蚀区所占的比例增大，并在一定程度上抑制了初生Al6Fe块状相的生成，当TiC含量达到10％（质量分数）时，出现了大尺寸TiC颗粒聚集现象，同时生成少量初生Al6Fe块状相。     

An analysis of strengthening mechanisms in a mechanically alloyed,oxide dispersion strengthened iron aluminide intermetallic

An iron aluminide alloy of base composition Fe-40Al has been prepared by mechanical alloying and processed using a variety of powder consolidation methods and heat treatments to produce a range of grain sizes and oxide dispersoid sizes. The strengths of these materials have been determined at room temperature and related to the various aspects of microstructure. Fine dispersoid particles may pin grain boundaries and help determine the fine grain size and contribute very significantly to the material strength. Grain size strengthening is shown to be a rather small component of the material strength, with the matrix strength being rather high for this intermetallic. The influence of other factors such as texture and the direction of application of stress (tension or compression) are also briefly discussed.