Diamond/Cu composites are widely studied as a new generation of thermal management materials in the field of electronic packaging and heat sink materials. The surface modification of diamond can improve interfacial bonding between the diamond and Cu matrix. The Ti-coated diamond/Cu composites are prepared via an independently developed liquid-solid separation (LSS) technology. It is worth noting that there are obvious differences for the surface roughness between the diamond-{100} and -{111} face by AFM analysis, which may be related to the surface energy of different facets. In this work, the formation of titanium carbide (TiC) phase makes up the chemical incompatibility between the diamond and copper, and the thermal conductivities of 40 vol.% Ti-coated diamond/Cu composites can be improved to reach 457.22 W·m−1·K−1. The results estimated by the differential effective medium (DEM) model illustrate that the thermal conductivity for 40 vol.% Ti-coated diamond/Cu composites show a dramatic decline with increasing TiC layer thickness, giving a critical value of ~260 nm.

Diamond/Al composites have been considered as the new generation of thermal management material. The critical challenge is that Al4C3 with deteriorating properties is easily generated at the interface of composites by conventional powder metallurgy and infiltration processes. This paper presents an independently developed liquid-solid separation (LSS) technology for fabricating diamond/Al composites with Cr-coated diamond particles. The key parameters of the LSS process such as the blank heating rate and its heating mode, the squeeze casting temperature and pressure, and pressurization time were optimized. Cr coating of the diamond particles led to improved interface characteristics. The higher thermal conductivity of diamond/Al composite with Cr-coated diamond particles is attributed to the favorable interfacial products of Al13Cr2 and AlCr2. Thermal conductivity of 40 vol.% Cr-coated diamond particles reinforced diamond /Al composites prepared by LSS with the optimal process was 309.20 W m−1 K−1, 108.06 % higher than that of the composite without the Cr coating. The results showed that relative density is a critical factor in optimizing of the bending strength, compressive strength, and thermal conductivity of the composites. No harmful intermetallic Al4C3 is generated at the interface of the composite. LSS technology is the new low-cost and compact method for the fabrication of diamond/Al composites with high thermal conductivity, which has the prospect of industrial application.

Rapid development of high-power electronic equipment for 5G and other advanced communication devices leads to a highly compact component size with increased heat flux density in integrated circuits, which requires electronic packaging materials to meet excellent heat dissipation performance. In this work, a novel liquid-solid separation technology was used to prepare a 40% (volume fraction) diamond/Al composite for electronic packaging substrates. By SEM, EPMA, and XRD techniques to investigate the fracture morphology and interface structure of the composite, the influence of diamond particle sizes (90, 106, 124, and 210 mu m) on the thermophysical properties of diamond/Al composite was studied. The results showed that with the increase of a diamond particle size, the density of a composite material increased first and then sharply decreased and attained the optimal value when the diamond particle size was 106 mu m. No harmful intermetallic Al4C3 was generated at the interface of the composite material. Coefficient of thermal expansion (alpha(c)) of the composite material increases slightly with increase in diamond particle sizes and remains relatively stable. The Kerner model can accurately simulate the alpha(c) of the diamond/Al composite. Thermal conductivity (lambda) is also affected by diamond particle sizes and interface behaviors, and the trend of change in lambda with the size of the diamond particles follows a similar trend to that between the density of composites and the particle size. The diamond/Al composite with diamond particle size of 106 pm has the best overall performance, relative density and alpha(c) attained 97.12% and 12.4 x 10(6) K respectively lambda is 153.1 W/(m.K), meeting 69.31% of the Maxwell-Eucken model prediction value. The airtightness value meets the military standard for this type of an electronic packaging material.

The electronic packaging shell, the necessary material for hermetic packaging of large microelectronic device chips, is made by mechanical processing of a uniform block. However, the property variety requirements at different positions of the shell due to the performance have not been solved. An independently developed liquid–solid separation technology is applied to fabricate the diamond/Al composites with a graded distribution of diamond particles. The diamond content decreases along a gradient from the bottom of the shell, which houses the chips, to the top of the shell wall, which is welded with the cover plate. The bottom of the shell has a thermal conductivity (TC) of 169 W/mK, coefficient of thermal expansion (CTE) of 11.0 × 10−6/K, bending strength of 88 MPa, and diamond content of 48 vol.%. The top of the shell has a TC of 108 W/mK, CTE of 19.3 × 10−6/K, bending strength of 175 MPa, and diamond content of 15 vol.%, which solves the special requirements of different parts of the shell and helps to improve the thermal stability of packaging components. Moreover, the interfacial characteristics are also investigated. This work provides a promising approach for the preparation of packaging shells by near-net shape forming.

The coefficients of thermal expansion (CTE) and thermal conductivity (TC) are important for heat sink applications, as they can minimize stress between heat sink substrates and chips and prevent failure from thermal accumulation in electronics. We investigated the interface behavior and manufacturing of diamond/Cu composites and found that they have much lower TCs than copper due to their low densities. Most defects, such as cavities, form around diamond particles, substantially decreasing the high TC of diamond reinforcements. However, the measurement results for the Cu-coated diamond/Cu composites are unsatisfactory because the nanosized copper layer on the diamond surface grew and spheroidized at elevated sintering temperatures. Realizing ideal interfacial bonding between a copper matrix and diamond particles is difficult. The TC of the 40 vol.% Ti-coated diamond/Cu composite is 475.01 W m−1 K−1, much higher than that of diamond/Cu and Cu-coated diamond/Cu composites under equivalent manufacturing conditions. The minimally grown titanium layer retained its nanosized and was consistent with the sintering temperature. Depositing a nanosized titanium layer on a diamond surface will strengthen interfacial bonding through interface reactions among the copper matrix, nanosized titanium layer and diamond particles, reducing the interfacial thermal resistance and exploiting the high TC of diamond particles, even if defects from powder metallurgy remain. These results provide an important experimental and theoretical basis for manufacturing diamond/Cu composites for heat sink applications.

采用Al-Si-P中间合金对Al-25％Si合金熔体进行变质处理,研究了P含量和变质温度对初生硅尺寸和形态的影响规律.利用金相显微镜、扫描电子显微镜观察了硅相和AlP化合物的形态,X射线衍射仪测定了变质细化合金的衍射图谱和择优取向.利用最小二乘法计算了硅相的点阵常数.结果表明,当加热温度为880℃、保温时间为30 min时,在Al-25％Si合金熔体中加入0.07％P可以将初生硅相细化至50μm以下.其相关细化机理为,一方面Al-Si-P中间合金内生的AlP化合物在熔体中溶解后重新析出,增加了异质形核的核心,使晶粒细化.另一方面,P变质使初生硅相晶面间距和点阵常数增大,生长过程中的择优分布消失,抑制了晶粒长大,使晶粒尺寸减小.但随着P添加量增加以及变质温度的升高,熔体中的AlP化合物溶解度增大,不利于晶粒细化.

The austempered ductile iron (ADI) grinding balls were austenitized at 900 °C for 2 h and then incomplete quenched in a sodium silicate solution for 100 s, after that austempered in an isothermal furnace at 230 °C for 1 h. Different from the two-step austempering process, this process can prepare a two-phase structure through the incomplete quenching stage and austempering stage, so we called it a dual-matrix structure (DMS) two-step austempering. This work aims to investigate the effect of different concentrations of sodium silicate (30 wt.%, 40 wt.%, 50 wt.% and 60 wt.%) as the incomplete quenching medium on the microstructure and properties of ADI. The microstructure, mechanical properties and wear resistance of ADI were analyzed using SEM with EDS, hardness testing (rockwell) apparatus and impact-toughness tester, as well as friction wear testing and impact wear testing. The result shows that the martensite and lower ausferrite phase in the DMS grinding balls gradually transform to lower ausferrite and upper ausferrite with increasing concentration of quenching liquid. As the sodium silicate concentration increased from 30 wt.% to 60 wt.%, the lower ausferrite volume fraction has initially increased and then decreased. DMS two-step austempering with a 40 wt.% sodium silicate produced the grinding balls with lower ausferrite and a small amount of tempered martensite that has the best overall mechanical properties and wear properties, which were suitable for application of large grinding machines. Besides, this work developed a new method to replace the salt bath austempering process, which was environmentally friendly.

利用大蒜渣负载型纳米零价铁对脱除水中Cu2+的反应行为和效果进行了探索,并对其脱除机理做了探讨.试验发现,在初始Cu2+浓度20 mg/L、pH=4,固液比为25 mg/15 mL的条件下,用负载纳米零价铁的大蒜皮对废水进行吸附,废水中Cu2+的去除效率最高可达94.15％.

Paddy field soil contaminated by cadmium may produce cadmium-contained corns causing Itai-itai disease, and in situ washing of soil with the organic acid is a good technical choice due to its convenience and cost-effectiveness. While the bottleneck of this technique is how to recycle the huge volume of washing effluent in an efficient and economical way. Biosorption of cadmium on the garlic peel was attempted in present study and it was found quite satisfactorily effective to remove all cadmium from the real soil leaching effluent after three-time sequential adsorption. The systematical investigation on the effect of various parameters on the adsorption of cadmium on garlic peel in the existence of tartaric ligand was performed and it was found that tartrate could change Cd2+ into Cd(tar)0 species whose electrical charge state would restrain its approach to the adsorbent particles. The porous microstructure in the transversal surface of garlic peel and the abundant groups of −COOH are the main factors affecting the adsorption capability. A demonstrative flowsheet of soil remediation by chemical washing coupled with biosorption was proposed correspondingly, in which the cadmium could be recovered from the soil washing effluent, and the recovered effluent was reused for next soil washing, and recovered garlic peel was reused for cadmium adsorption from the effluents again, showing a great prospect in the remediation of paddy field soil contaminated by cadmium.

Nano-zero-valent iron has been widely used in the field of environmental pollution control due to its high efficiency of reduction and environmental friendliness. This study discusses the preparation of nano-zero-valent iron as well as the comparison of the characteristics of several nano-sized zero-valent iron preparation methods. In this study, we also aimed at the quantitative evaluation of the zero-valent iron reduction activity of nano-particles, and proposed an analytical test method based on the − + 2 3 4 CrO Cr system. The method is sensitive and accurate in measurement and can be applied to the quantitative determination of the zero-valent iron reduction activity evaluation. On this basis, we made a comparative study of the retention ability of the prepared nano-zero-valent iron in reducing activity under a variety of storage conditions, screening and determining the appropriate storage medium, storage time and other conditions, and it was found that anhydrous ethanol can be used as a storage medium, 60% absolute ethanol + 40% deionized water for three days, the reaction time of one hour, to keep the reduction effectiveness of freshly prepared samples. Research can provide valuable reference and guidance for the preservation and transportation of nano-zero-valent iron materials. The basic data obtained in this work will be of good reference for improving the preparation, storage and application of the existing nano-zero-valent iron materials.

In this paper,the merits and demerits of the main treatment methods of heavy metal electroplating wastewater in our country were reviewed.The advantages of biomass adsorption treatment methods were summarized.Prospects for future application of biomass adsorbents in electroplating wastewater treatment were expected.The related contents provide useful reference for the application of biomass adsorption materials in the process design and engineering application of electroplating wastewater treatment.

Paddy field soil contaminated by cadmium may produce cadmium-containing corn due to the paddy's strong ability to accumulate cadmium. The in situ washing of soil with an organic acid is one of the suitable technical choices for the remediation of cadmium-contaminated soils. The limiting factor of this method lies in the recycling and reuse of the huge amount of washing effluent in an efficient and economical way. In present study, the simulated solutions were used to examine the adsorption efficiency of cadmium on a biosorbent which was synthesized by using garlic peel as the raw material. The biosorption behavior of cadmium on garlic peel was systematically studied in the presence of a citrate ligand. Presented here for the first time, garlic peel with buoyant properties was carefully collected and used for the preparation of the adsorbent, and verified to have a prominent advantage in efficiently separating from the solution after adsorption because of its floatability. Results show that the presence of citrate has a significant inhibition effect on the adsorption behavior of cadmium on the floating garlic peel, at the optimal pH of 4.0, which can be ascribed to the competitive affinity to the cadmium from the citrate ligand. SEM shows that floating garlic peel has a ruffled epidermis in the flat surface and porous microstructure in the transversal surface, making it durable enough and favorable for adsorption; and -COOH was determined by FTIR to be the main functional group contributing to the adsorption capability of garlic peel. Cadmium can be eluted off the garlic peel after adsorption, and the garlic peel can be then reused for the next cycle of adsorption with little decrease in adsorption capacity, even after ten adsorption/desorption cycles. The real leach liquor of cadmium-contaminated soil sample by 0.01 mol L-1 citric acid solution was used for testing, and it was found that after three adsorption uses, almost all the cadmium in the leach liquor had been recovered by the floating garlic peel. The above research results provided a possible route to recycle the soil washing solution by biosorption, giving a great perspective in the remediation of paddy field soil contaminated by cadmium.

A liquid-solid separation technology (LSS) is applied to fabricate near-net shape packaging shells made of hypereutectic Al-Si composites with gradient distributions of the microstructure and properties. This new technology solves the problem of the formation of coarse flake primary Si, which will seriously deteriorate the mechanical properties of the materials, and unavoidable with conventional casting method. The microstructure of the hypereutectic Al-Si composite were characterized using scanning electron microscope, energy dispersive spectroscopy and transmission electron microscope. In order to eliminate the influence of crystal defects and stress, the effects of annealing treatment on the thermal expansion coefficient and thermal conductivity of the composites were also investigated. The results show that the volume fraction of Si decreases along a gradient from the bottom centre of the packaging shell, which houses the chips, to the top of the packaging wall, which is welded with the cover materials. The bottom of the shell has a CTE of 11.7 x 10(-6) K-1, TC of 124.3Wm(-1) K-1, and primary Si content of 53.7%. The top of the shell has a CTE of 18.4 x 10(-6) K-1, TC of 151.2Wm(-1) K-1, and primary Si content of 23.3%. Such a distribution enables a good matching of the thermal expansion behaviour of the packaging shell with the chips, which have typically low CTE, while avoiding the issue of poor soldering performance of Al/Si alloys. In addition, it reduces the internal stress of the shell due to integrated forming technology. (C) 2018 Elsevier B.V. All rights reserved.

Wastewater produced from the soil washing process contains heavy metals, which limits its reuse for washing. So it is necessary to develop an efficient and economical way to recycle it, and this study presents a biosorption method to realize this goal. A typical soil sample contaminated by lead was taken from the real field near a lead smelting factory, used for the toxic metals extraction with dilute citric acid. A leach liquor was obtained with lead ions at the level of 12.35 mg/L, Cd 1.2 mg/L, Cu 1.5 mg/L, Zn 2.6 mg/L, as well as the coexisting anions such as sulphate, silicate, chloride at the concentration of sveral hundred miligram per liter. The garlic peel was modified by a simple chemical saponification process and used as the biosorbent for toxic metal removal. Firstly, the adsorption behavior of lead ions on the saponified garlic peel was systematically investigated using the synthetic solutions, and then the adsorption mechanisms were explored by detailed experiments combining with the thermodynamic calculation reuslts of the aqueous system of Pb(II)-citrate-H2O. It was found that in artificial solution containing 0.01 mol/L citrate, the maximum adsorption capacity of 261.0 mg/g was reached at pH near 3.0, and also at this very pH value the Pb2+ and Pb(H2Cit)+ were the dominant lead species which are favorable for adsorption due to its easier approaching to the —COO–ligands in the saponified garlic peel partilces via charge attraction, and the appearance of Pb(HCit)0 and Pb(Cit)– at pH above 3.0 inhibits the adsorption. Secondly, the real leach liquor was used for adsorption tests, and twice adsorption under the optimal conditons would decrease the residual concentrations of Pb, Cd, Cu and Zn to zero. After elution by using 0.1 mol/L nitric acid, the adsorbed metals can be recovered and garlic peel be reused for at least 10 cycles effectively. This study presents a prospective biosorption method for economical and efficient removal of the lead ions from soil washing wastewater with citric acid as the leaching reagent.

In order to prolong the life of inner liner of coke can, the thermal fatigue property of Cr17Mn10 heat-resisting steel was analyzed from cast mirostructure, the morphologies of surface and cross-section of the thermal fatigue crack, thermal fatigue damage factors by OM, SEM, photoshop and image tool software. The initiation and propagation rules of thermal fatigue crack were studied. The results show that under 1100 ℃ high temperature and room- temperature water cooling for 300 times, Cr17Mn10 heat resistant steel has good thermal fatigue property. The cracks of the samples mainly appear in the phase interfaces between carbides and matrix interface, ferrite and austenite interface, and the grain boundary. The thin, deep cracks with high concentration are beneficial to relaxing the elastic strain energy. Single and thick crack is easy to become wide and deep, which is bad for the thermal fatigue property of the material.

Low-cost and good quality Al–diamond composites were prepared in the application of heat dissipation using an advanced liquid–solid separation technology. Their thermal conductivity (TC) and coefficient of thermal expansion (CTE) were measured, especially on the effect of diamond particle surface metallization. The TC of composites reinforced with Ni-coated diamond particles was found to have increased by almost 80 % compared to that of Al alloys. The diamond surface in the composites was characterized using an electron microprobe, X-ray diffraction and SEM. It was found that high TC of the composites was obtained due to the generation of Al4Ni3 and AlNi phases at their interfaces between Al and diamond. In addition, the theoretical calculation for TC and CTE of the composites show the similar tendency with their experimental data.

High performance diamond/Al composites for heat dissipation were manufactured by advanced cost-effectiveliquid-solid separation (LSS) technology. The effect of Cu coating on the interface bonding and thermal conductivity ofcomposite materials were researched. The fracture morphology and interfacial behavior of composite materials wereanalyzed by SEM, EMPA and XRD. The result show that the Al2Cu4 compounds form from coating element diffuse andAl matrix, which can enhance the interfacial bonding between the two phases and improve the properties of the materials.After Cu coating, the density of the composites increases by 1.16%, the thermal conductivity increases by 9.50%, thetensile strength increases by 17.39%. The thermal physical properties of Cu-diamond/Al are better than that of CE13(controlled expansion) alloy. Additionally, the experimental data of thermal conductivity and coefficient of thermalexpansion of diamond/Al composites show the similar tendency with those by Maxwell and Kerner models, respectively.

The oxidation resistance of iron-based superalloy with different Si content at 1 250 ℃ was studied using XRD,SEM and EDS techniques.The results show that the sequence of oxidation resistance of the iron-based superalloys at 1 250 ℃ from superior to inferior is 0.93％Si ＞ 0％Si ＞ 2.76％Si ＞ 1.40％Si.The reason for the outstanding oxidation resistance of iron-based superalloy with 0.93％Si is that dispersively distributed SiO2 particle layer is formed between the matrix and its compact oxide film.These small SiO2 particles join the oxide film closely and play a role of pinning as chocks,which improves the adhesion property of oxide film,and thus the oxidation resistance of the material is improved.

The method of adding modifier with rapid cooling to improve the morphology and size of primary silicon in Al-27Si alloy,were investigated.The statistics and analysis of morphology,size,roundness,grain fineness distribution of primary silicon in Al-27Si alloy were studied by OM and Image Plus software.The results show that better method of adding modifier with rapid cooling for refining primary silicon of Al-27Si,amount of modifier with 0.09％,temperature with 880 ℃,time with 30 min,and cavity diameter with 10 mm in diameter of cooling mold.The descend order of influencing factors to size of primary silicon is amount of modifier,rate of cooling same to time,and temperature.

The paper studies the effect of different concentration of sodium silicate as the quenching medium on the structure and performance of 100 mm diameter grinding balls with the new technology of step austempering. The microstructure, mechanical properties and wear resistance of ADI grinding balls are analyzed by means of OM, SEM/EDS, rockwell apparatus, impact-toughness tester, friction wear testing machine and impact wear testing machine. The result shows that the ADI grinding balls processed by quenching liquid of 40 % concentration sodium silicate have ideal performance. Lower Bainite, as main components of the matrix structure of the ADI grinding balls, making the rockwell hardness 53 HRC, the impact toughness up to 12 J/cm2, the abrasion loss only 0.5 mg, the impact wear loss 1379 mg, work hardening making the rockwell hardness up to 56 HRC. The comprehensive mechanical properties and wear properties of the ADI grinding balls processed by quenching liquid of 40 % concentration and temperature of 40-60 degrees C sodium silicate have the most excellent manufacture stability are more suitable for the application in the condition of grinding of large grinding machine.