TiB2 reinforced Ti(C,N)-based cermet was produced by the reaction spark plasma sintering of Co, Ni, Ti, C, BN, Mo2C, WC, and TaC mixtures. To understand the mechanism of reaction sintering, systematic investigation on the microstructure evolution and displacement variation rule was carried out. In addition, the influence of C/BN molar ratio on the microstructures and performances of cermet was investigated. Except an initially increased pressure, three densification patterns were found. The first method was the CoTi, TiNi, and Ti-BN diffusion reactions, resulting in a shrinkage of 22.06%. The second pattern was the viscous flow and dissolution-reprecipitation, which corresponded to the synthesis of Ti(C,N) and TiB2. In this process, the shrinkage ratio was increased by 35.62%. The final densification mainly originated from the viscous flow of metallic binder. It contributed to the transformation of macrovoids into microvoids, and an increased displacement of 30.10%. With the increasing of C/BN ratio, more C atoms diffused into Ti(C,N). Furthermore, core/rim structure-Ti(C,N) and coreless (W,Mo,Ta,Ti)(C,N) were fabricated. However, the microvoids in cermets enhanced. As a result, the hardness and fracture toughness first increased and then decreased. Results from this work are helpful to understand the reaction spark plasma sintering technique, and can enrich the preparation method of cermet.

为研究应用于汽车的波纹状磁流变制动器在磁流热场强耦合作用下的温度特性,建立了磁流变制动器的磁流耦合和热流耦合有限元分析模型,采用直接序贯耦合法得到磁流变制动器的磁场分布和稳态非制动工况、正常制动工况、紧急制动工况、连续间歇制动工况下的温度分布及其变化规律.研究结果表明,在稳态非制动工况,磁流变制动器温度分布近乎均匀,而在正常制动、紧急制动工况和连续间歇制动工况下的最高温度分别为92.4℃、111.2℃、80.4℃,制动间隙内的温度均呈现先上升后下降的变化趋势;随着励磁电流的增加,磁流变制动装置在制停过程中的最高温度也逐渐上升,但其上升幅度越来越小.研究结果可为磁流变制动器的设计和应用提供参考依据.

In order to improve wear resistance, the Ni/WC composite coating was prepared on NAK80 mold steel surface by laser cladding technology. Phase and microstructure had been investigated by scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS) and X-ray diffraction (XRD). Dry sliding tribological properties at room temperature of the coating had been researched by ball-on-disc wear tests. Results indicated that phase constituents of the coating were mainly composed of WC, W2C, Cr23C6, NiCr, CrB2 and gamma-Ni, etc. There was a chemical metallurgical bonding between the coating and the steel substrate. Higher wear resistance of NAK80 mold steel was achieved after cladded by the Ni/WC composite coating, which was mainly related to dendrite phases Cr23C6 and hard phases WC, W2C dispersing in the coating.

本文分析了我校材料成控专业人才培养方向单一化的弊端,探讨了我校材料成控专业为拓宽人才培养的方向、充实人才培养的内涵所进行的探索和实践。

The Ni-based WC composite(Ni-WC) coating on mould steel 2738 was prepared by CO2 laser cladding.The substrate 2738 steel and the Ni-based WCCC were tested under dry sliding friction conditions to investigate their friction and wear behavior.The wear volume of specimen was measured using a 3-D surface profilometer,and the worn surface topography was observed by the scanning electronic microscopy.The results show that the microhardness of the Ni-WC coating was enhanced significantly,its surface hardness exceeded 1200 HV,ensuring its wear resistance.The average friction factor was about 0.25,it decreased by about 44% in comparison with that of the substrate 2738 steel of 0.43.WC hard phase enhanced the bearing capacity of the friction surface,reduced the wear rate by 96.7%.The abrasive wear was the main wear mechanism for the Ni-WC coating.

Carbon foams were prepared by a polymer sponge replication process and their microwave absorbing properties were investigated. The electric conductivity of carbon foam has a direct effect on its microwave absorbing property, as the carbon foam with a medium electric conductivity of 0.46S/m has got a relatively excellent microwave absorbing property and demonstrated a characteristic of broadband absorption. Some structure modification has been made on carbon foams to fruther imrove their microwave absorbing performance. The result shows that making slots, especially gradient slots on the surface of carbon foams can greatly improve their microwave absorbing properties, while the reflection coefficients for a three-layered carbon foam structure exceeds -10dB with the combination effect of multilayer structure design and parameters gradient variatioin in the whole frequency range of 2.6-18GHz, which is usually to be considered as the practical application standard for microwave absorbing materials.

A review was given about the research progress of laser cladding coating in relation to general coating,composite coating and non-crystalline coating.Suggestions were provided with respect to existing problems and future directions of laser cladding coating.

The Ni-based WC alloy coatings were successfully fabricated on NAK80 mold steel by Nd:YAG and CO2 lasers. The microstructure and properties of the laser cladded coatings were analyzed by SEM, EDS, XRD and microhardness tester. The results show that phase constituents of both coatings are mainly composed of tungsten carbide (WC+W2C), Cr23C6, NiCr, CrB2 and γ-Ni. The excellent metallurgical bondings have formed at the interface between the substrate and the laser cladded coatings. Dendrite and white and block WC phase were observed in two kinds of laser cladded coatings, but the dendrite in Nd:YAG laser cladded coating is more fine. The microhardness of NAK80 mold steel is greatly improved by laser cladding, however the microhardness of the CO2 laser cladded coating is even higher than the Nd:YAG laser cladded coating.

Superfine coatings have been attempted to prepare by Electro-spark deposition (ESD) on cast steel substrate. The microstructures and properties of the coating were investigated by X-ray diffractometer (XRD), scanning electron microscopy (SEM) and microhardness tester. The results show that ultra-fine particles prevail in the coating. The primary phases of the coating contain Fe3W3C, Co3W3C, Si2W and W2C. Its average microhardness reaches 1511.75 HV. The results of abrasive test demonstrated that the coating had an excellent sliding wear resistance because the superfine particles distributed dispersedly in the coating increased the resistance to micro-cutting and plowing during the wear test, which effectively improves the surface performance of cast steel substrate.

The Ni-based tungsten carbide alloy coating was fabricated on NAK80 mold steel by laser cladding technology.The characteristic of microstructure,micro-hardness and the formation mechanics were examined.The results show that the metallurgical bonding is good between the cladding coating and the steel substrate,the microstructure of laser cladding coating is composed of fir-tree crystal Cr23C6,un-melted tungsten carbide granular crystal,γ-Ni solid solution and NiCr,CrB2.The micro-hardness of laser cladding coating is considerably higher than the substrate,so the wear-resisting property of mold surface is improved to some extent.

Electrospark Deposition is a new technique for strengthening on surface of metal material.The ESD coatings have good properties of high hardness,wear resistance,temperature resistance and corrosion resistance.Advantages,the latest development of research and the application in surface treatment of mold are introduced in this paper,and suggestions on the intensive research and application of electrospark deposition are proposed.

According to the characteristics and the teaching present status of material formation equipment curriculum,the reform measures of teaching modes were introduced,namely adjusting teaching contents,reforming teaching method and strengthening cultivation of practice competence,the good achievement was obtained,which provides the basis for teaching reform of curriculum of the same kind.

Carbon nanotubes (CNTs) decorated by graphitic shells encapsulated Cu nanoparticles were fabricated by low-energy hydrocarbon ion deposition with using Cu as hold substrate at 900°C. Scanning electron microscopy shows that the surface of CNTs becomes very coarse by hydrocarbon ion treatment. The investigation of transmission electron microscope shows that the full surfaces of CNTs are coated by dense graphitic shells encapsulated Cu nanoparticles. The graphitic shells consist of 7–10 layers and the size of Cu core is 1–2 nm.

The Co-based alloy coatings were successfully fabricated on H13 steel by Nd:YAG and CO2laser. The microstructure and properties of the laser cladded coatings were compared and analyzed by SEM, EDS, XRD and microhardness tester. The results show that the excellent metallurgical bonding has formed at the interface between substrate and laser cladded coatings. Cellular crystal at the bonding zone, cellular dendrite at the central zone and reticular equiaxed crystal near top surface were observed in Nd:YAG laser cladded coating, while the typically hypoeutectic character was found in CO2laser cladded coating. Phase constituents of both coatings are mainly composed of Cr23C6, Co3Mo2Si, MoC, FeCr and γ-Co. The microhardness of H13 steel is greatly improved by laser cladding, however the microhardness of the CO2laser cladded coating is even higher than the Nd:YAG laser cladded coating.

以培养材料成型及控制工程专业学生CAD/CAM/CAE应用能力为目标,提出在材料成型CAD/CAM/CAE课程教学中采用项爵驱动教学模式,以提高教学效果.采用项目驱动教学法有利于学生培养应用CAD/CAM/CAE来分析、解决工程实际问题的能力,建立具备一定CAD/CAM/CAE技术的现代机械设计理念.

Carbon foams with a reticulated macrostructure were prepared by a polymer sponge replication method. The electromagnetic parameters of carbon foams with variable electric conductivity were measured at a frequency of 2450MHz. Compared with the same composition pulverized powders, carbon foams have relatively lower dielectric constant but much larger dielectric loss, and more remarkably, carbon foams have magnetic loss. The microwave absorbing property measurement of carbon foams was also conducted. A relatively broad absorbing band performance has been got for carbon foams, and the absorbing values exceeds 7dB almost in the whole measured frequency range of 4–15GHz, while the frequencies range for absorbing values exceeding 8dB are about 7 GHz for the carbon foam with an electric conductivity of 0.46S/m. It is worthy that the broad absorbing band feature of the carbon foam is obtained without any impedance match design, which indicates carbon foams have a great possibility of being applied as RAMs. The special electromagnetic loss characteristics and prominent radar absorbing properties about carbon foams indicate macrostructure modification is possibly a new and effective way to modulate the electromagnetic properties of RAMs besides the traditional composition variation.

In this paper the importance of surface treatment for moulds and various surface treatment methods were introduced, specifically the electron-spark surface treatment was explained, including its characteristics, principle and application as well as its comparison with laser surface treatment. The electron-spark surface treatment technology on moulds has an advantage of effective, low cost, environment protective and so on, so it is practically valuable and especially suitable to develop for the mould manufacture enterprises in Taizhou city, famous asthe capital of mould.

In this paper the teaching reform research and practice in the mould specialty in Taizhou University,a typical local university,was discussed,which is designed to train more applied high-quality professionals for local enterprises.

模具CAD/CAM/CAE课程教学中构建项目驱动教学模式,有利于学生提高CAD/CAM/CAE工程能力,锻炼学生独立处理、解决模具工业中实际问题的能力。

Carbon foams were prepared by a polymer sponge replication method and their microwave absorbing properties were investigated in this paper. It was found that the electric conductivity of carbon foams increases quickly with the improvement of carbonization temperatures. Moreover, the electric conductivity of carbon foams strongly affects their microwave absorbing performances. As the electric conductivity increases from 0.02 S/m to 1.03 S/m, the dominant electromagnetic behavior of carbon foams changes from transmission to reflection with regard to the incident electromagnetic wave. The best microwave absorbing performance was achieved for the carbon foam with an electric conductivity of 0.46S/m when other parameters are fixed at constants, and absorbing values for the carbon foam exceeds 7dB almost in the whole measured frequency range of 4-15GHz, while the frequencies range for absorbing values exceeding 8dB are about 7 GHz, demonstrating a characteristic of broad absorbing bandwidth. It is to be noted that the absorbing characteristic for the carbon foam with an electric conductivity of 0.46S/m is obtained without any impedance match design, which indicates that carbon foams have the possibility to be applied as broad absorbing bandwidth RAMs.