K. Zangeneh-Madar

Bio: K. Zangeneh-Madar is an academic researcher from Malek-Ashtar University of Technology. The author has contributed to research in topics: Microstructure & Sintering. The author has an hindex of 12, co-authored 24 publications receiving 399 citations. Previous affiliations of K. Zangeneh-Madar include Islamic Azad University.

Evaluation of microstructure and contiguity of W/Cu composites prepared by coated tungsten powders

Abstract: In this paper, infiltration behavior of W/Cu composite compacts made from coated tungsten powder has been investigated. For this purpose, tungsten particles were coated with Ni, Ni–P and Ni–Cu–P using electroless plating technique. Then the coated tungsten powders were compacted under selective pressures for control infiltrated copper in range 10–20 wt%. Infiltration process was carried out at 1300 °C under a reducing atmosphere. The effect of pre-coat of tungsten particles on microstructure, contiguity and density of infiltrated W/Cu compacts was evaluated by OM/SEM, EDS and Archimedes methods. It was found that electroless plating of tungsten particles leads to more homogeneity microstructure so relative density of 99.3% was achieved for infiltrated compacts. The contiguity of W–W particles in the microstructure of composite made from Ni–Cu–P coated tungsten powder was lower than to other ones.

Improvement of physical properties of Cu-infiltrated W compacts via electroless nickel plating of primary tungsten powder

Abstract: In the present research, tungsten particles were coated using nickel/nickel–phosphorus electroless plating technique. The coated tungsten powders were pressed under constant pressure to achieve compact material of cylindrical shape with same porosity. Then, attained compacts were infiltrated/penetrated by liquid copper under the hydrogen atmosphere in order to obtain W–15 wt.% Cu composites. The coated/uncoated powders as well as its infiltrated compacts were characterized by optical microscopy (OM) as well as scanning electron microscopy (SEM), EDS and XRD methods. The microstructure, relative density and specific resistivity of composites were compared. The microstructural observations revealed that the infiltration behavior can be improved in the compacts prepared by both nickel and nickel–phosphorus coated tungsten powders, in comparison with uncoated ones. In addition, it was found that relative density may be raised from 95% by nickel electroless plating, that leads to decrease specific resistivity from 6 to 4 µΩ cm. Enhancement of electrical conductivity of infiltrated W–15 wt.% Cu compacts prepared by electroless nickel coated tungsten powders was related to its higher density.

The effect of additive and sintering mechanism on the microstructural characteristics of W–40Cu composites

Abstract: In this research, effect of cobalt and nickel additives on the W–40wt.% Cu composites prepared by solid phase sintering and infiltration (SPS + I) as well as liquid phase sintering (LPS) processes has been investigated. For this purpose, three types of powder consist of pure tungsten, mixture of tungsten–1wt.%Co and mixture of tungsten-1wt.%Ni were separately prepared and compacted by cold isostatic pressing (CIP). In the SPS + I process, compacted specimens were sintered at 1100 °C for 1 h and subsequently infiltrated by liquid copper at 1250 °C for 1 h. In the LPS process, compacted samples were directly infiltrated without initial sintering. Density of samples was measured by Archimedes method. Microstructure (i.e. contiguity, porosity, grain size) and chemical composition were studied by SEM and EDS, respectively. It is found that microstructural characteristics of the W–40wt.%Cu composites depend on sintering mechanism as well as additive type. Density of samples prepared by LPS process was higher in compared with ones obtained via SPS + I process. This behavior was related to W–W contiguity as well as tungsten particles wettability.

Mutual dependency of mechanical properties and contiguity in W–Cu composites

Abstract: The solid–solid and solid–liquid interfaces and their relationship to mechanical properties have been investigated in tungsten powder compacts infiltrated with copper. The application of Ni, Ni–Cu and Ni–Cu–P electroless coatings on primary W powders, prior to compaction was found to affect the contiguity and hence improve the yield and compressive strength of specimens. Scanning electron microscopy, X-ray diffraction analyses and mechanical properties were investigated with due allowance for the participation of contiguity in microstructure. Comparison of the observed data was made with those of conventional elementally mixed compacts. It was illustrated that the application of thin elemental or complex coating has a direct influence on the contiguity and mechanical properties. It was found that W powder coated with Ni–Cu–P coating exhibited the lowest contiguity, and highest relative density.

Electroless nickel plating on AZ91 Mg alloy substrate

Abstract: Electroless Ni-plating on Mg alloy AZ91 has been studied to understand the effect of the substrate microstructure and roughness on the deposition rate, nucleation, coating microstructure, and mechanical property of the coatings. Experimental results indicate that the growth of Ni deposit in the early stage was influenced by the substrate microstructure and roughness. The electroless Ni-plating on the abrasive blasted AZ91 (rough) substrate showed a higher deposition rate than that on the finely polished one, indicating that the mechanical roughening enhances the nucleation and coalescence of Ni crystallites. Scratching tests showed that higher coating adhesion is achieved on the roughened AZ91 substrate. Wear tests, however, showed that the Ni plating on the rough substrate has a higher friction coefficient than that on the polished surface. The hardness and adhesion property of Ni coatings before and after heat treatment were also characterised.

A review on the mechanical methods for evaluating coating adhesion

Abstract: Coatings have been applied widely in aerospace, biomedical, electronic, and many other industries. The performance of a coating is dictated by the adhesion between the coating and the underlying substrate. Thus, the evaluation of coating adhesion is critical for the assessment of the quality of a coating and its fitness for service. However, this evaluation is not straightforward, and various mechanical and non-mechanical evaluation methods have been developed. This paper presents a comprehensive review of the currently most widely employed mechanical methods. The interface fracture mechanics that provides the fundamental knowledge for conducting adhesion assessment and analysis is briefly introduced. Detailed discussions are presented on various sandwich specimen-based and bimaterial specimen-based testing methods, with emphasis on the principles, merits, limitations, typical applications, and recent improvements of each method.

Self-lubricating Ni-P-MoS2 composite coatings

Abstract: Tribological coatings with low coefficients of friction are in high demand by various industries since they can improve machine efficiency and have an environmental impact. A self-lubricating Ni-P-MoS2 composite coating has been successfully deposited on a mild steel substrate by electrodeposition. The effects of MoS2 on the tribological coatings have been investigated. Compared to a pure Ni-P coating, the Ni-P-MoS2 composite coating exhibited a dramatic reduction in friction coefficient against a bearing steel ball from 0.45 to 0.05. Examination and analysis of the worn surfaces and wear debris, the composite coating showed minimum wear and oxidation compared to the severe wear and oxidation observed in the pure Ni-P coating. The evolution of MoS2 particles in sliding wear has been elucidated.

Recent progress in development of tungsten-copper composites: Fabrication, modification and applications

Abstract: Tungsten copper (W-Cu) composites, as a traditional refractory material, are promising materials for manufacture of electrical contacts and electrodes, heavy duty electronic contacts, welding and electro-forging dies, heat sinks, packaging material, arcing resistance electrodes and thermal management devices owing to their excellent properties. This critical review presents and discusses the current progress of W-Cu composites. Starting with an introduction of the synthesis methods for W-Cu composites, including the conventional and modern preparation approaches. After that we focus on the description of the improvement of mechanical properties and arc-erosion properties by modification techniques. Finally, the advantages of W-Cu composites in applications such as electrical contacts, electronic packaging materials, and heat sinks, as well as military materials, are described, respectively.