Papers by Keyword: Surface Properties

Abstract: In this study, Al and N implantation effect on surface properties of 4H-SiC epitaxial layers were investigated before annealing process. AFM results indicated that all implanted samples indicated relatively low RMS roughness values. From UPS and XPS analysis, work function and Si-C binding energy of implanted samples were increased compared to the reference 4H-SiC sample. Those variations may be caused by lattice disorder and amorphization. In addition, TEM image showed damaged area in 4H-SiC epitaxial layer.

Abstract: Metal hollow mini-spheres (MHMS) present a basis for the creation of new structured materials due to their low weight and energy adsorption capacity. Typically, MHMS are made of steel with a high level porosity in the sphere’s wall 80-110 microns thick. Modification of the outer surface by copper coating of 20-30 microns imposed by vacuum sputtering provides several times higher electrical conductivity, lower porosity of the outer layer and smoother surface, preserving light weight and flotation properties. This modification will provide better possibilities for spheres’ consolidation by means of sintering and electric brazing and creation of new cellular structures.

Abstract: Laser shock processing (LSP) is increasingly applied as an effective technology for the improvement of metallic materials’ mechanical and surface properties in different types of components, mostly as a means of enhancement of their fatigue life behavior. As reported in previous contributions by the authors, a main effect resulting from the application of the LSP technique consists in the generation of relatively deep compression residual stresses fields into metallic components allowing an improved mechanical behaviour. On the other hand, Mg and its alloys have gained increasing relevance as natural biomaterials as their mechanical properties are in the same range as those corresponding to natural bone as well as due to their inherent bioabsorbable properties. In the present paper, the application of the LSP technology to biocompatible bioabsorbable Mg alloys suitable for chirurgical implementation is envisaged, the experimental verification of the residual stresses fields induced and the experimental characterization of the surface properties introduced by means of the treatment being specifically considered.

Abstract: Titanium dioxide is currently the most important white pigment material used in the world and its surface properties are very important for consumer industries such as paints, papermaking and plastics. If agglomerates are present, the down-stream product properties such as gloss, opacity, and storage stability will be greatly affected. The addition of organic surface treatment agents onto the surface of titanium dioxide particles can change its surface: reduce the inter-particle forces to reduce particle agglomerates; change the hydrophobic or hydrophilic properties of particle surface to enhance the compatibility with the solvent, water, or organic resin; can also improve the particle mobility and industrial processing. Therefore, it is very important to fully understand the interaction mechanism between pigment particles and functional organic surface treatment agents. This paper summarizes the related research results and progress.

Abstract: This article gives a brief description of metal oxides, acceptable for using in advanced conductometric gas sensors, as well as a consideration of approaches, that can be used to select metal oxides for the manufacture of devices intended to sensor market.

Abstract: This paper presents a laser melting of high thermal conductivity steel (HTCS) dies for surface properties modification due to die failures during operations. Sample were cut from as-received die without any defect or crack. Melting process was conducted using Nd:YAG laser system with pulse mode at 50 W average power. The laser beam was defocused to a spot size of 1 mm on the sample surface. Parameters controlled in this study were peak power of 800 and 1200 W, and pulse repetition frequency of 80 and 90 Hz. Metallographic study and chemical composition analysis were conducted using Hitachi TM3030Plus scanning electron microscope (SEM) and energy dispersive x-ray spectrometer (EDXS). Surface roughness was measured using Mitutoyo SURFTEST SJ-410 stylus profilometer. Hardness properties of the modified layer were characterized by Wilson Hardness tester at 100 N force. The metallographic study showed high porosity at partially melted zone (PMZ) area. From overall findings, laser processing parameter affected hardness properties and surface roughness of modified layer. Where the surface roughness value obtained is between 1.49 and 3.15 μm, while the hardness value is between 550.9 and 610.9 HV_0.1. These findings are significant to parameters selection for hot stamping die surface repair and prolong its service.

Abstract: Wood plastic composite (WPC) materials represent modern materials that are attracting interest worldwide. WPC are composite materials and they have properties of both components – plastic and wood. WPC materials are formed by combining two substances – discontinuous reinforcements (wood particles or cellulose microfibers) and a continuous binder (plastic matrix), in a certain proportion. The authors describe WPC machined surfaces after turning. On the basis of a set of experimental data collected by surface and mechanical tests obtained from the WPC materials, the mechanical deformation work was evaluated, the value of which presents specific information about the material as a specific material coefficient.

Abstract: Heat treatments of alloys in fluidized bed reactors have been carried out for more than twenty-five years. Recently this technology has been used for surface engineering applications in the deposition of hard and/or corrosion resistant layers e.g. aluminizing, chromizing, nitriding, carburizing, boronizing. The fluidized bed method is simple, efficient, environmentally friendly and capable of immediate adjusting the furnace atmosphere for specific requirements e.g. production of multielement coatings. The boride coatings on steel have an excellent combination of properties e.g. high fatigue strength and wear resistance. On the other hand silicide coatings are well known for their excellent corrosion resistance. Boron-siliconizing in fluidized beds is a promising method to improve both the wear and corrosion properties of steels. In the present paper fluidized bed technology (FBT) was used to deposit boride and boron-silicide coatings on steels. The coatings were examined by means of electron and optical microscopy and X-Rays diffraction, in terms of the coatings composition, morphology, thickness and phase formation. The coatings tribological properties were evaluated under dry wear.

Abstract: Laser shock processing (LSP) is increasingly applied as an effective technology for the improvement of metallic materials’ mechanical and surface properties in different types of components, mostly as a means of enhancement of their fatigue life behavior. As reported in previous contributions by the authors, a main effect resulting from the application of the LSP technique consists in the generation of relatively deep compression residual stresses fields into metallic components allowing an improved mechanical behaviour. In this paper, the special case of Ti6Al4V alloy is considered from a more fundamental point of view, with specific consideration of the microstructural changes and residual stresses fields justifying those macroscopic effects. From a concrete point of view, the effect of the application of different typical LSP intensities on the microstructure and residual stresses fields introduced in this material and their possible correlation to the associated surface effects are analyzed.

Abstract: In this study, 12 commercially available paper towels were collected from the market. Their shearing properties were evaluated by Kawabata Evaluation System for Fabric (KES-F). Three properties namely: (i) coefficient of friction (MIU), (ii) deviation of MIU (MMD) and (iii) geometric roughness (SMD). Experimental results revealed that the surface properties varied within the products. When different properties were correlated, it was found that there was not significantly relationship between MIU, MMD and SMD. However, weight and thickness had well statistically relationship to SMD.