Papers by Keyword: Surface

Abstract: The article deals with photo-reflective layer on Low Temperature Co-fired Ceramic substrate deposition. Measurement of diffusion and specular reflectance and roughness of layer is included. Fabrication process and its optimization is also mentioned. For measurement of deposited layer optical properties, spectrometric method in spherical chamber was used. Further, profile of layers surface was measured by profilometer to acquire dependence between roughness and reflectivity. The main aim of work is to map the possibility of creation of photo-reflective layer on electrical, chemical and thermal resistant substrate in simple way.

Abstract: The efficiency of vibrating machines will be greatly improved with the proper working parameters. A new type of hydraulic vibration pile driver extractor is presented in this paper. The machine-pile-soil dynamic model of the hydraulic vibration pile driver extractor based on frictional forces and vibration coupling is established with frictional forces of the pile-soil contact surface and the resistance force of the pile-end. Furthermore, the nonlinear dynamical characteristics of the dynamic model are studied and the influences of different system working parameters on frictional forces of pile-soil interface, working efficiency and capability are discussed by numerical simulation. The different working parameters are exciting force, frequency and stiffness. The results show that the suitable parameters of the vibrating machine can change the soil characteristics and decrease the frictional forces of the pile-soil interface. The work can provide useful guidance for the research on the vibration friction, selection in the suitable parameters of interface surface in engineering and design in the development of such machines.

Abstract: Titanium alloys corresponding to Ti-Nb-Zr-Ta system represent a new generation of biomaterials, which were developed for medical applications like metal-ceramic. They are composed of non-toxic and non-allergenic elements and have lower values of modulus of elasticity compared to that of the current biomaterials used in dentistry or orthopedics. In this paper are presented two new titanium alloys (Ti-21Nb-6Zr-15Ta and Ti-25Nb-10Zr-8Ta), which were characterized from structural aspect, mechanical and surface properties point of view using scanning electron microscopy, X-ray diffraction, wear properties, Vickers microhardness measurement. Also, was tested the cytotoxicity of these alloys using direct contact method. The results showed that the investigated alloys have a biphasic structure composed of β-solid solution with intragranular lamellar structures specific to α^”. The experimental results shown that new titanium alloys from the system Ti-Nb-Zr-Ta present much better properties compared to that of the metallic biomaterials used currently.

Abstract: The integral characteristics of triangulation 3D models of industrial products are considered. Absolute integral characteristics are presented by the following groups: linear, angular, surface and volume. For comparative evaluation the relative characteristics are proposed. The proposed integral characteristics are a component part of a morphological analysis system of 3D models.

Abstract: The traditional approach to grinding is to operate within the limits of surface quality. The requirements for surface quality in grinding are higher than those in other common machining operations such as turning and milling. The surface quality of machined parts is very important for precise production and assembly. When we focus on roughness parameters after grinding, we can establish the limits of these parameters for typical grain materials: Al₂O₃, SiC, CBN, SG and others. Increasing demands on accuracy and quality of production leads to research concerned with the properties of these materials and the surface quality after grinding. This paper shows new possibilities for the ground surface with focus on surface roughness obtained under varying combinations of cutting conditions. The influence of the grinding wheel, cutting parameters and coolant on higher surface quality is assessed by roughness parameters Ra, Rz, Rt and the Material portion of a surface profile. These high-precision ground surfaces are shown to have a Nanometres (10^-9) unit topography demonstrating that the process is able to replace other finishing technologies such as superfinishing or honing.

Abstract: A number of machine parts are provided with design notches for the mounting of lock ring, position of bearing, and cross over sub of diameters etc. These elements significantly affect the durability of machines parts and their influence is inherently implemented into their design. The question is machining itself, particularly ambient surface finishing and intrinsic notch element. The changes and behaviour of machined surface form also very interesting part of paper and particularly under load. A number of new findings concerning the influence of machining on durability of machine parts both under dynamic load and the cyclic tensile, bending at rotation and torque were discovered in this research. The findings are important for further development, mainly related to car and aviation industries.

Abstract: In this article, the potassium permanganate solutions (KMnO₄) was used to treat the PPTA fiber based on an orthogonal experimental design. The optimum conditions of KMnO₄ treatment were concentration of 20%, temperature of 30°C and treating time of 20min. The interfacial properties of aramid fiber/epoxy composites were investigated by the single fiber pull-out test (SFP), and the results showed that the interfacial shear strength (IFSS) of aramid/epoxy composites was remarkbly improved.

Abstract: Using the radio frequency magnetron sputtering that directly bombardment A1N target under different sputtering-power and total pressure to deposit the A1N thin films. The crystal structure, composition, surface and refractive index of the thin films were studied by XRD, SEM, AFM and elliptical polarization instrument. The results show that the surface and refractive of the thin films strongly depends on the sputtering-power and total pressure,the good uniformity and smoothness is found at 225 W, Ar flow ratio 5.0 L_Ar/sccm, substrate temperature 100°Cand 1.2 Pa. All film thickness are from 60 to 80nm, and the highest N/Al mole ratio reach to 0.83.The crystal structure of the as-deposited thin-films is amorphous，then it transforms from blende structure to wurtzite structure as the rapid thermal annealing(RTA) temperature changes from 600 to 1200°C. The refractive index also increases with the RTA temperature it is increasing significantly from 800 to 1000°C. When the Annealing temperature at 1000°C, we get the best uniformity and smoothness of the surface of the film.

Abstract: Micron-sized WC-CrCNi powder (WC-metal powder, WC 68%, C 0.56%, Cr 21% Ni 6%) was coated onto magnetic shaft material Inconel718 (In718) surface using HVOF thermal spraying equipment for the improvement of the surface properties of the shaft. During the HVOF coating, metal carbides, such as WC and Cr₇C₃ decomposed to W₂C, metals and free carbon. The free carbon and the excesively sprayed oxygen formed carbon oxide gases and thus produced pores and voids in coating. The optimal coating process (OCP) that produced the lowest coating surface porosity and the highest surface hardness was determined by the Taguchi experimental program of nine processes for four spray parameters with three levels. Coatings with porosity 1.20±0.1% and hardness 1150±60 Hv were prepared using optimal coating processes. The coating was porous, but the hardness was improved approximately three times from 400±10 Hv (In718) to 1150±60 Hv (coating). Friction coefficients (FC) of the coating were lower compared with In718 at both 25°C and 450°C. FC decreased with increasing temperature from 25°C to 450°C for both In718 and the coating. Wear depths of coatings were smaller than those of In718 at both 25°C and 450°C. For the improvement of the surface properties and durability of the magnetic shaft, HVOF WC-CrCNi power coating was recommended.

Abstract: The studies presented in this paper show a concept for setting up a milling process with intentionally invoked chatter vibrations. The process is used for the generation of surface structures on forming tools. Wear of the milling tool is investigated as well as the tribological characteristics of the surfaces. The results lead to the conclusion that this method is suitable for machining challenging materials like high speed steel.