oalib
Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
Structure and properties of multicomponent coatings deposited onto sialon tool ceramics  [PDF]
D. Paku?a
Archives of Materials Science and Engineering , 2011,
Abstract: Purpose: The aim of this paper is to investigate structure, mechanical and functional properties of sialon tool ceramics with wear resistant multicomponent coatings deposited with PVD method.Design/methodology/approach: The structural investigation includes the metallographic analysis on the scanning electron microscope. Examinations of the chemical compositions of the deposited coatings were carried out using the X-ray energy dispersive spectrograph EDS, and glow-discharge optical emission spectroscope GDOS. The investigation includes also analysis of the mechanical and functional properties of the material: microhardness tests of the deposited coatings, surface roughness tests, evaluation of the adhesion of the deposited coatings and tribological test made with the pin-on-disk”.Findings: Deposition of the multicomponent coatings with the PVD method, on tools made from sialon’s ceramics, results in the increase of mechanical properties in comparison with uncoated tool materials, deciding thus the improvement of their working properties.Practical implications: The multicomponent coating carried out on multi point inserts (made on sintered sialon’s ceramics) can be used in the pro-ecological dry cutting processes without using cutting fluids. However, application of this coating to cover sialon ceramics demands still both elaborating and improvement adhesion to substrates in order to introduce these to industrial applications.Originality/value: The paper presents some researches of multicomponent coatings deposited by PVD method on sialon tool ceramics.
Thermal Residual Stresses in Multilayered Coatings
Xiancheng ZHANG,Binshi XU,Haidou WANG,Yixiong WU,
Xiancheng ZHANG
,Binshi XU,Haidou WANG and Yixiong WU State Key Laboratory of Metal Matrix Composites,Shanghai Jiao Tong University,Shanghai,China National Key Laboratory for Remanufacturing,Beijing,China

材料科学技术学报 , 2005,
Abstract: The mechanical integrity and reliability of coated devices are strongly affected by the residual stresses in thin films and coatings. However, due to the metallurgical complexity of materials, it is rather difficult to obtain a closed-form solution of residual stresses within multilayered coatings (e.g. functionally graded coatings, FGCs). In this paper, an analytical model is developed to predict the distribution of residual stresses within multilayered coatings. The advantage of this model is that the solution of residual stresses is independent of the number of layers. Specific results are obtained by calculating elastic thermal stresses in ZrO2/NiCoCrAIY FGCs, which consist of different material layers. Furthermore, the residual stress distribution near the edges and the stress-induced failure modes of coating are also analyzed. The topics discussed provide some insights into the development of a methodology for designing fail-safe coating systems.
Tribological properties of CrNx coatings  [PDF]
B. Warcholinski,A. Gilewicz
Journal of Achievements in Materials and Manufacturing Engineering , 2009,
Abstract: Purpose: The purpose of this work is the characterization of the tribological properties thin Cr-N coatings, both monolayer Cr2N, CrN coatings and multilayer Cr/CrN, Cr2N/CrN coatings, deposited by cathodic arc physical vapour deposition (CAPVD).Design/methodology/approach: The deposition parameters of Cr2N and CrN were determined. Structure of the coatings were investigated using the scanning electron microscopy (SEM). The XRD examination was carried out to specify the phase structure, EDS to define the chemical composition of the coatings. The investigation includes also microhardness, roughness tests, adhesion, friction coefficient and wear rate.Findings: Basing on the scratch test it was shown that the influence of the architecture on the coating’ adhesion is dominant. It was found that the all tested coatings show high critical load Lc2 >70 N. The multilayer coatings show higher critical load when compared to monolayer coatings.Research limitations/implications: The main limitation of this work is linked to the deposition technique itself.It is difficult to avoid surface defects and pinholes that strongly influence the tribological results.Practical implications: Chromium based coatings present good mechanical properties which allow them to be used in several applications; from decorative to protective coatings.Originality/value: The comparison of adhesion and wear resistance of mono- and multilayer coatings based on chromium. The deposition technology enable to obtain the coatings with high adhesion to the substrate. This may be important to advanced coatings industry.
Properties of the multicomponent and gradient PVD coatings  [PDF]
L.A. Dobrzański,L.W. ?ukowska
Archives of Materials Science and Engineering , 2007,
Abstract: Purpose: This paper presents investigation results of the properties of the multicomponent (Ti,Al)N and gradient Ti(C,N) wear resistant coatings, deposited with the PVD process onto the substrate from the cemented carbides, cermets and Al2O3+TiC type oxide tool ceramics.Design/methodology/approach: The methodology includes analysis of the mechanical and functional properties. The Ra parameter was assumed to be the value describing surface roughness. The microhardness tests using the Vickers method were made with use of dynamic ultra microhardness tester. The measurements were made in the load - unload” mode. Tests of the coatings adhesion to the substrate material was made with use of the scratch test. Surface roughness tests were done both before depositing the coatings and after completing the PVD process. Cutting properties of the investigated materials were determined based on the technological continuous cutting tests of the EN-GJL-250 grey cast iron.Findings: Main properties of the investigated materials were introduced. It has been stated, that properties of the cemented carbides, cermets and oxide tool ceramics with deposited multicomponent (Ti,Al)N and gradient Ti(C,N) PVD coatings increase in comparison with uncoated material. Multiple increase of tool life result among other things from almost double increase of microhardness of PVD coated materials in comparison with uncoated cemented carbides, cermets and oxide tool ceramics, increasing of thermal and chemical wear resistance and improving of chip formation and removing process’ conditions.Practical implications: Pro-ecological dry cutting processes without the use of the cutting fluids and in the Near-Net-Shape” technology.Originality/value: Application of multicomponent (Ti,Al)N and gradient Ti(C,N) types of coatings onto sintered tool materials in order to improve cutting properties of tools.
Synthesis and Characterization of Multilayered Diamond Coatings for Biomedical Implants  [PDF]
Leigh Booth,Shane A. Catledge,Dustin Nolen,Raymond G. Thompson,Yogesh K. Vohra
Materials , 2011, DOI: 10.3390/ma4050857
Abstract: With incredible hardness and excellent wear-resistance, nanocrystalline diamond (NCD) coatings are gaining interest in the biomedical community as articulating surfaces of structural implant devices. The focus of this study was to deposit multilayered diamond coatings of alternating NCD and microcrystalline diamond (MCD) layers on Ti-6Al-4V alloy surfaces using microwave plasma chemical vapor deposition (MPCVD) and validate the multilayer coating’s effect on toughness and adhesion. Multilayer samples were designed with varying NCD to MCD thickness ratios and layer numbers. The surface morphology and structural characteristics of the coatings were studied with X-ray diffraction (XRD), Raman spectroscopy, and atomic force microscopy (AFM). Coating adhesion was assessed by Rockwell indentation and progressive load scratch adhesion tests. Multilayered coatings shown to exhibit the greatest adhesion, comparable to single-layered NCD coatings, were the multilayer samples having the lowest average grain sizes and the highest titanium carbide to diamond ratios.
Виб р проектування технолог й поверхнево обробки TRIBOLOGICAL COATINGS SELECTION AND DEVELOPMENT Выбор и проектирование технологий поверхностной обработки  [cached]
Larisa A. Lopata,Yuri V. Brusilo
Proceedings of National Aviation University , 2010,
Abstract: Розглянуто стратег ю та методолог ю вибору оптимально поверхн обробки для деталей вузл в тертя. Запропоновано схему розробки операц йно технолог поверхневого опрацювання нанесення покриття. The strategy and methodology for selecting of optimal surface treatment for a given tribological application are the main objectives of study. The scheme of development of operation technology of surface treatment and coating deposition is proposed. Рассмотрены стратегия и методология выбора оптимальной поверхностной обработки для деталей узлов трения. Предложена схема разработки операционной технологии поверхностной обработки и нанесения покрытий.
Nanoscale Multilayered ZrAlN/ZrB2 Coatings Synthesized by Magnetron Sputtering
Dejun LI,
Dejun
,LI

材料科学技术学报 , 2006,
Abstract: Multilayered ZrAlN/ZrB2 coatings containing alternating bilayer periods were synthesized by dc magnetron sputtering technique. The intensities of ZrN (111) or ZrN (200) textures in the structure of the nanolayers depended on the bilayer period as well as N2 gas partial pressure during deposition. Nanoindentation testing showed that hardness and internal stress of the nanolayers varied with the bilayer period and crystallographic orientation in the coatings. The hardness of the nanolayers with bilayer periods of 3~6 nm was enhanced (~27%) over the rule-of-mixture value. A low percent of N2 in processing gas was proved to be benefitial to the synthesis of high hard nanoscale multilayered coatings.
Sintered tool materials with multicomponent PVD gradient coatings  [PDF]
K. Go?ombek,J. Miku?a,D. Paku?a,L.W. ?ukowska
Journal of Achievements in Materials and Manufacturing Engineering , 2008,
Abstract: Purpose: The main aim of researches was investigation of structure and properties of the (Ti,Al,Si)N gradient wear resistant coatings.Design/methodology/approach: The structural investigations include the metallographic analysis on the transmission and scanning electron microscope. Examinations of the chemical compositions of the deposited coatings were carried out using the X-ray energy dispersive spectrograph EDS, glow-discharge optical emission spectroscope GDOES, auger electron spectroscope (AES) and using the X-ray diffractometer. The investigations include also analysis of the mechanical and functional properties of the materials: substrate hardness tests and microhardness tests of the deposited coatings, surface roughness tests, evaluation of the adhesion of the deposited coatings as well as cutting properties.Findings: Deposition of the multicomponent gradient coatings with the PVD method, based on the Al and Si solid secondary solution in the TiN titanium nitride, isomorphous with the alternating pure titanium nitride TiN, on tools made from oxide, nitride ceramics and tool cermets, results in the increase of mechanical properties in comparison with uncoated tool materials, deciding thus the improvement of their working properties.Practical implications: Deposition of (Ti,Al,Si)N nanocrystalline coatings by the use of PVD method causes the increase of cutting properties of tools made of cermets for ca. 300% and of Al2O3+ZrO2 for ca. 100% comparing to adequately uncoated tools.Originality/value: Comparison of the wide range of modern sintered tool materials with wide unique set of PVD coatings.
TRIBOLOGICAL PROPERTIES OF TiBx AND WC/C COATINGS  [PDF]
FRANTI?EK LOFAJ,MARIAN MIKULA,BRANISLAV GRAN?I?,GREGORZ CEMPURA
Ceramics-Silikáty , 2011,
Abstract: Tribological properties of TiBx and WC/C coatings have been studied using the ball-on-disc method at room and elevated temperatures in air to investigate their behavior under conditions approaching high performance dry cutting. The average room temperature coefficients of friction (COF) of both nanocomposite DC magnetron sputtered TiBx coatings and PECVD WC/C coatings were in the range 0.2-0.6. The lowest value of TiBx coatings of 0.16 was achieved in case of prefferentially oriented stuctures deposited at the highest negative bias. The lowest COF of WC/C was around 0.11. The increase of testing temperature to 450°C caused the increase of COF up to approximately 0.7-0.8. The experiments at elevated temperatures suggest the existence of the oxide transfer film with higher COF than that of the sliding contact without the film. Although both coating systems have relatively high COF values at elevated temperatures, they exhibit elements of some adaptive behavior.
Tribological Behavior of Thermally Sprayed WC Coatings under Water Lubrication  [PDF]
Chaoqun Zhang, Masahiro Fujii
Materials Sciences and Applications (MSA) , 2016, DOI: 10.4236/msa.2016.79045
Abstract: Thermally sprayed coatings have been used in various fields of industry for enhancing surface characteristics of materials and extending their service life. The contact surface of some mechanical equipment such as the fine pulverization equipment which is used in the woody biomass production process is required to have wear resistance in the water environment. Thermally sprayed coatings would be a good candidate to improve surface wear resistance under water lubrication. The objective of this study was to evaluate the tribological performance of thermally sprayed coatings under water lubrication. Thermally sprayed coatings which were classified into WC, WB and Ni spraying of three categories were compared with water-lubricated sliding test at a sliding velocity of 0.02 m/s and mean pressure of p0 = 10 MPa with a ring-on-disk apparatus. Thermally sprayed coatings showed comparatively high friction coefficient and well wear resistance under water lubrication. WC contained coatings showed better wear resistance than WB and Ni coatings. Thermally sprayed coatings showed obviously different mechanical properties and tribological behaviors, and the effect of wettability and hardness on tribological characteristics was discussed under water lubrication. Friction coefficient increased as the surface contact angle of thermally sprayed coatings increased. The wear rate decreased as the surface hardness of thermally sprayed coatings increased. Wear resistance of thermally sprayed coatings was excellent under water lubrication. WC contained coatings showed lower wear rate than WB and Ni coatings. WC-14CoCr coating showed the lowest wear rate.
Page 1 /100
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.