Papers by Keyword: Composite Layer

Abstract: 3D stacking technology with TSV interconnect is becoming a major trend of microsystem packaging. Redistribution layer (RDL) plays an important role in TSV packaging applications. Inorganic RDL based on AlN/sodium silicate composite through wet process has been put forward in this paper. After mixing AlN powder with sodium silicate uniformly and curing of the mixture, AlN/sodium silicate composite dielectric was formed. Finally a novel wet RDL process was developed for TSV interposer applications.

Abstract: In order to improve the high temperature oxidation resistance, 75 Si-Fe and the silver paint were selected as cast-penetrated agent using the cast-infiltration method to form an aluminum silicon composite layer on the heat resistant steel grate surface. The microstructure and hardness properties of cast-infiltration layer were studied by optical microscope (OM), scanning electron microscope (SEM) with electron dispersive spectrum (EDS), and micro hardness test. The results show that the cast-infiltration layer is composed of ferrite and irregular shape of carbide particles. Most of the carbides are (Fe,Cr)₃C and a small amount (Fe,Cr)₇C₃ also observed in composite layer. The highest micro hardness of fine carbide particles reaches 1253 HV. The optimized silicon content is 50wt%, and the thickness of infiltration layer reaches 0.6mm.

Abstract: Wear is a common problem for engineering components subjected to dynamic loading. Surface modification is mostly applied to reduce the wear. An exploratory research is conducted to form a composite coating on AISI 4340 steel surfaces by incorporating a mixture of TiC and hexagonal Boron Nitride (h-BN) particulates using powder placement and TIG torch melting techniques. Initial results show the evidence of TiC incorporation in all tracks but the presence of h-BN is limited in a few tracks. However, processing conditions are identified that can produce composite coatings incorporating both TiC and h-BN particulates. The melt microstructure consists of a small amount of un-melted TiC and h-BN, partially melted TiC particulates with eutectic structure containing precipitated TiC and TiB2 particles. Hardness of the coating is found to fluctuate along the melt depth. However, the maximum hardness of the coating is about 3 times the base hardness of 250 HV.

Abstract: Nanometer Ni-AlN composite layers were prepared by electrodeposited technology. The optimum technological parameters of nanometer Ni-AlN composite layers were obtained by experiments and analysis. We observed surface morphology and metallurgical structure of composite layers with scanning electron microscope (SEM) and high respective transmission electron microscope (HRTEM). The test results showed that the nanometer Ni-AlN composite layers prepared by proper ultrasonic-electrodeposited technology have better wear resistance and corrosion resistance. And the composite layers consist of AlN particles and nickel grains both nanometer-sized.

Abstract: The formation of hard surface layer on steel provides a protective coating against wear, thermal loads and corrosion. In the present work a hard composite layer is formed on steel surfaces by preplacement of titanium powder and melted under nitrogen environment. Surface melting was conducted using TIG torch with different energy inputs. The microstructure and the morphology of the melt tracks were investigated using SEM and X-ray diffraction. The in-situ melting of titanium powder in nitrogen atmosphere produced dendritic microstructure of titanium nitride. The melt layer contained dispersed TiN, Ti2N dendrites highly populated at the surface compared to the deeper melt and gave a maximum surface hardness of around 1927 Hv. The wear property of the melt track was investigated using pin-on-disk tribometer at room temperature. The modified surface layer gave a low friction value of 0.12 and wear rate of 0.007895 ×10-4 compared to 1.648 × 10-4 mm3/N/m for the uncoated steel surface.

Abstract: The possibility of forming a TiN dispersed composite layer on steel was studied by preplacement of titanium powder on steel surface and melting under TIG (Tungsten inert gas) torch in a reactive environment. The surface melting of preplaced 1.8 mg/mm2 Ti powder was performed under TIG torch with energy inputs of 324,378 and 432 J/mm in a pure nitrogen environment. With these melting conditions, the powder layer along with a thin layer of the substrate melted and produced a melt pool of around 1mm thickness. The resolidified melt layer consisted of dispersion of TiN dendrites in ferrite matrix and thus a composite of TiN in ferrite is created on the steel surface. The concentration of dendrite population was found to be higher nearer the melt surface compared to the deeper depth. A maximum surface hardness of about 2000 Hv was developed at the surface when glazed with an energy input of 432 J/mm and the hardness decreased gradually away from the surface. The hardness development is directly related to the concentration of TiN dendrites.

Abstract: In this paper, a micro-arc oxidation (MAO) approach is introduced for “in-situ” preparing TiO2 composite layer upon the surface of titanium alloy (Ti-6Al-4V) substrate. The surface morphologies, chemical compositions, crystal microstructure and photocatalytic properties of the layers were investigated by using a field emission scanning electron microscope (FE-SEM), energy dispersive spectrometer (EDS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), electro-chemical workstation and UV-Vis spectrophotometer. The experimental results revealed that photocatalytic performance of the TiO2 composite layers was much higher than that of the pure TiO2 layer and also exhibited absorption under the visible light irradiation.

Abstract: A composite layer was prepared on the Ti-6Al-4V alloy surface by ion nitriding, magnetron sputtering Mo and ion sulfurizing composite treatment technique. The phase structure, morphology, and cross-sectional element distribution of composite layer were analyzed. Friction and wear properties of composite layer were tested by MM-200 laboratory tester. XRD analysis showed that the composite layer was mainly comprised of Ti, Mo, MoS2, TiN, and transition layer. This composite layer is perfect wear-resistant surface due to existence of self-lubricating MoS2 on hard Mo and TiN layers with good anti-friction ability. Thereby, the results of friction and wear test showed that anti-wear performance of Ti-6Al-4V alloy after composite treatment was remarkably improved under dry and sliding conditions. Both the friction coefficient and the wear loss of the nitriding-Mo plating-sulfurizing layers were lower than that of the nitriding layer due to the formation of the MoS2 layer on Mo and TiN layers.