Surface coatings in tribological and wearresistant applications

Abstract

Surface engineering has become a key technology in advanced applications in recent decades, offering materials surfaces with special physical, chemical or mechanical properties. Several new processing techniques have been developed, some of which are successfully applied industrially, for example to allow surface design and manufacture of wear-resistant mechanical parts. To illuminate understanding of surface engineering in tribological applications, a detailed review of surface coating technologies in tribological and wear-resistant applications is presented.     

IFHTSE Global 21: heat treatment and surface engineering in the twenty-first century: Part 9 – Influence of materials science on heat treatment and surface engineering

Abstract

Significant progresses have been made in the past decades in the discipline of materials science, which include, but not limit to, the synthesis of new materials, advancement in analytical and experimental techniques, sustainable and environmentally friendly processing technologies, computational material science and nanotechnology. These developments have major influences on the research and application of heat treatment and surface engineering, and provide new opportunities to engineer the surfaces of new and conventional materials using advanced technologies to meet the ever increasing demands in surface and subsurface related properties. This survey gives a brief review on some aspects of heat treatment and surface engineering which keep pace with new developments in materials science. The specific areas being examined include: (i) advanced analytical techniques; (ii) sustainable and environmentally friendly technologies; (iii) surface engineering of emerging new materials such as intermetallic compounds, shape memory alloys and biomaterials; (iv) the search for superhard coatings and surface nanostructured materials; (v) mathematical modelling of surface engineering systems.     

Residual stresses and distortions in welded structures: a perspective for engineering applications

Abstract

In this paper, some of the historical developments and recent advances in understanding welding induced residual stresses and distortions are discussed in the context of their impact on today's engineering applications. With recent rapid advances in computational simulation techniques, the complex thermomechanical phenomena associated with typical welding processes can be effectively dissected into solvable problem sets for both fundamental understanding and specific engineering applications. Although a great deal of research is currently still ongoing to advance our fundamental understanding of the complex thermophysical and thermomechanical phenomena, an engineering perspective is provided to demonstrate how an engineer can make use of the current state of knowledge to derive effective practical solutions when dealing with day to day problems in the areas of residual stresses and distortions in welded structures. First, some of the fundamental mechanical considerations associated with residual stress and distortion developments are presented. Then, some of the computational modelling requirements for engineering applications are discussed in the light of recent developments. Finally, application examples are presented to demonstrate how an effective engineering solution can be sought by taking advantage of today's advanced modelling techniques with appropriate engineering assumptions.     

Metal finishing: enhanced performance achieved through plasma processing

Abstract

This paper provides an overview on how plasma deposited coatings can significantly enhance the surface properties of metallic components. Two plasma processing technologies known as physical vapour deposition (PVD) and plasma enhanced chemical vapour deposition (PECVD) are introduced. Examples of the coatings deposited using these two processes are discussed. Among the coating application areas outlined are their use to increase the wear life of tools, to improve decorative finish and to enhance medical device biocompatibility.     

Surface Treatment of Crl2MoV Steel towards Long-Life Cold-Work Dies

SURFACE ENGINEERING technologies such assurface nitriding,carburizing and oxidation,are veryeffective in strengthening surfaces and thus improvingthe wear resistance of tools and dies.In resent years,there is an ever-increasing interest in the developmentof various thin coatings via different physical vapordeposition(PVD)techniques to improve thetribological properties of tools,dies,drills and machineelements(e.g sliding bearings,seals and valves)[l-6].Especially,PVD Ti/TiN coating h…     

Surface Treatment of Cr12MoV Steel towards Long-Life Cold-Work Dies

With the rapid development of the automobile industry in China, there is an ever-increasing demand for long-life cold working dies used for punching automobile components. However, the full potential of such advanced surface engineering technologies as PVD coatings and duplex surface treatments in cold work dies has not been realized. In the present study, Crl2MoV steel has been surface engineered by single PVD Ti/TiN coating and duplex treatment combining low temperature plasma nitriding (LTPN) with PVD Ti/TiN coatings. The properties of Ti/TiN coatings in terms of surface morphology, microhardness, load bearing capacity, bonding strength and wear resistance were evaluated by microhardness,scratch and wear tests. The experimental results show that PVD Ti/TiN coatings can significantly enhance the surface load bearing capacity (especially for duplex treatments) and wear resistance of Cr12MoV steel by more than one order of magnitude. This can be mainly attributed to the hard and well-adherent PVD Ti/TiN surface coatings and strong mechanical support of the LTPN sublayer. While two-body abrasive wear prevails for uncoated Crl2MoV, the micropolishing action of the counterface dominates in surface engineered material.     

计算机辅助机械产品创新设计关键技术及应用研究

针对当前新产品开发的实际,对计算机辅助机械产品创新设计理论及关键技术进行研究.通过产品的需求分析、功能设计、价值工程分析,可使产品设计人员在机械产品的概念设计、方案设计以及工艺设计阶段,根据市场需求进行新产品开发,并迅速地找到已有产品的问题所在和改进创新方向,获得产品创新方案构思,从根本上解决机械产品设计中的技术难题而实现创新.     

The Efficacy of the Application of Highly Specialised Surface Engineering Methods in the Economy. Case Study.

NANOTECHNOLOGY,multifunctional materials andsurface engineering are dominating areas of scientificand technological development in Europe.It can beeseen in one of the main priorities of EU FP6,namelyPriority3NMP(Nanotechnologies and Nanosciences,Knowledge-based Multi-functional Materials and NewProduction,Processes and Devices)which is strictlyoriented on these particular problems.New tasks whichare foreseen to be financed within Priority NMP withinthe nearest call for proposal[1…     

CMAS corrosion of EB PVD TBCs: Identifying the minimum level to initiate damage

Over the last decade a significant amount of research has been conducted into the durability of thermal barrier coatings (TBCs) focusing mainly on issues of oxidation, erosion and foreign object damage (FOD). However, as the performance and durability of TBCs has improved the temperatures at which they operate has increased. This increase in temperature has resulted in another lifing issue for EB PVD TBCs, namely that of CMAS attack. Calcium–magnesium–alumino-silicate (CMAS) attack occurs when atmospheric dust that has deposited on the surface of turbine blades melts and wicks into the columns of the TBC. This occurs at temperatures above 1240–1260 °C and results in the degradation of the columnar microstructure of the TBCs. Due to the fact that TBCs operate in a temperature gradient CMAS only infiltrates part of the coating before solidifying.There are a number of issues associated with CMAS attack, both chemical and mechanical. From a chemical point of view CMAS attack of electron beam (EB) physical vapour deposited (PVD) TBCs can be considered as a form of corrosion; when there is a lot of excess CMAS on the surface of a coated component Yttria diffuses out of the TBC into the molten CMAS resulting in a t′ to monoclinic phase transformation in the yttria stabilised zirconia (YSZ), CMAS attack also results in localised melting and subsequent re-precipitation of the coating resulting in a loss of the defined columnar microstructure. While from a mechanical point of view the CMAS, once re-solidified, reduces the strain compliance of the EB PVD and can result in spallation of the TBC on cooling. Furthermore, current studies have indicated that small amount of CMAS infiltration significantly increases the erosion rate of EB PVD TBCs.This paper covers various aspects of CMAS attack of EB PVD TBCs, specifically looking at minimum levels of CMAS required to initiate damage, as well as investigating it from an erosion–corrosion perspective.     

PVD TBC experience on GE aircraft engines

The higher performance levels of modern gas turbine engines present significant challenges in the reli-ability of materials in the turbine. The increased engine temperatures required to achieve the higher per-formance levels reduce the strength of the materials used in the turbine sections of the engine. Various forms of thermal barrier coatings have been used for many years to increase the reliability of gas turbine engine components. Recent experience with the physical vapor deposition process using ceramic material has demonstrated success in extending the service life of turbine blades and nozzles. Engine test results of turbine components with a 125 μm (0.005 in.) PVD TBC have demonstrated component operating tem-peratures of 56 to 83 °C (100 to 150 °F) lower than non-PVD TBC components. Engine testing has also revealed that TBCs are susceptible to high angle particle impact damage. Sand particles and other engine debris impact the TBC surface at the leading edge of airfoils and fracture the PVD columns. As the impacting continues, the TBC erodes in local areas. Analysis of the eroded areas has shown a slight increase in temperature over a fully coated area ; however, a significant temperature reduc-tion was realized over an airfoil without TBC.     

Failure of physical vapor deposition/plasma-sprayed thermal barrier coatings during thermal cycling

ZrO₂-7 wt.% Y₂O₃ plasma-sprayed (PS) coatings were applied on high-temperature Ni-based alloys precoated by physical vapor deposition with a thin, dense, stabilized zirconia coating (PVD bond coat). The PS coatings were applied by atmospheric plasma spraying (APS) and inert gas plasma spraying (IPS) at 2 bar for different substrate temperatures. The thermal barrier coatings (TBCs) were tested by furnace isothermal cycling and flame thermal cycling at maximum temperatures between 1000 and 1150 °C. The temperature gradients within the duplex PVD/PS thermal barrier coatings during the thermal cycling process were modeled using an unsteady heat transfer program. This modeling enables calculation of the transient thermal strains and stresses, which contributes to a better understanding of the failure mechanisms of the TBC during thermal cycling. The adherence and failure modes of these coating systems were experimentally studied during the high-temperature testing. The TBC failure mechanism during thermal cycling is discussed in light of coating transient stresses and substrate oxidation.     

表面工程技术在海洋工程装备中的应用

随着我国对海洋资源开发和利用的快速发展,对先进海洋工程装备的需求日益强烈,尤其是对某些关键部件的表面性能要求越来越高。然而,单从提高材料自身性能的角度来满足对高性能的要求几乎是不可能的。表面工程技术是提高材料表面性能的重要方法,它能够在不破坏材料自身性能的前提下,对材料表面性能进行强化或再生,使材料或部件表面具备耐磨、耐蚀、抗氧化、耐热、绝缘、密封和隔热等性能中的一种或几种。因此,表面工程技术已成为实现海洋工程装备材料最终性能的重要手段。对海洋工程装备中涉及到的材料表面改性技术、应用和发展进行了综述。最后,指出了一些重要问题,展望了将来的研究方向。     

IFHTSE global 21: heat treatment and surface engineering in first decades of twenty-first century Part 5 – Modelling based design of surface engineered systems

Abstract

Aspects of surface engineering design, namely, simulation of processing and service behaviour and prediction of properties, are discussed and summarised. Available design techniques are demonstrated by means of examples. Two process simulation modelling approaches, relating to oxidation of Ti alloys and nitriding of steels, are described. A novel optimisation approach to extract Young's modulus, yield strength and work hardening exponent of a power law (load–displacement) material is presented. Design and service behaviour simulation case studies of surface engineered titanium alloy gears for the sports car industry are also presented. It is shown that advances in theoretical principles and computational methodologies and tools, together with the ever increasing abundance and accuracy of thermodynamics and kinetics databases of materials and processing atmospheres, have enhanced the reliability of surface engineering simulations to a level good enough for industrial application. Barriers and development trends in surface engineering design are also addressed.     

Microstructural and Tribological Characterization of Duplex Coatings with Additional Ion Bombardment

THE FILM DEPOSITION process exerts a number ofeffects such as crystallographic orientation,morphology,topography,densification of the films.The optimization procedure for coated parts could bemore effective,knowing more about the fundamentalphysical and mechanical properties of a coating,theirinterdependence and their influence on the wearbehavior.The effects on the structure as well asmechanical and tribological properties of the filmswere investigated in detail in the present research.…     

IFHTSE Global 21: heat treatment and surface engineering in the twenty-first century: Part 11 – Survey of the heat treatment and surface engineering industry in Argentina at the beginning of the twenty-first century

Abstract

Heat treatment and surface engineering are enabling technologies for modern industry in technologically developed countries. However, the technical requirements of industry in the developing countries, and particularly in Argentina, are often not so demanding. This article is an attempt to reflect the current status of heat treatment and surface engineering in Argentina at the beginning of the twenty-first century, particularly in terms of available technology and human resources. Emphasis is also given to the future prospects of this area of engineering.     

Effect of industrial surface finishes on heat treatment and surface engineering of steel

Abstract

The surface state of industrial parts is complex and effective heat treatment or surface engineering of such parts requires a precise knowledge of how the steel was produced and manufactured. During manufacturing a mechanical part will be subject to the actions of various tools, mechanical constraints and diverse: solids, liquids or gases. Current highly automated processes have introduced new materials and chemicals which change the characteristics of the surface and may generate defects or even scrap. A series of case studies is presented illustrating the problems arising from industrial processes and their solutions.     

Isothermal oxidation of physical vapor deposited partially stabilized zirconia thermal barrier coatings

Thermal barrier coatings (TBCs), consisting of physical vapor deposited (PVD) partially stabilized zirconia (PSZ, 8 wt.%Y₂O₃) and a diffusion aluminide bond coat, were characterized as a function of time after oxidative isothermal heat treatment at 1373 K in air. The experimental characterizations was conducted by X-ray diffraction analysis and scanning electron microscopy (SEM) with energy-dispersive spectroscopy. During cooling to room temperature, spallation of the PSZ ceramic coatings occurred after 200 and 350 h of isothermal heat treatment. This failure was always sudden and violent, with the TBC popping from the substrate. The monoclinic phase of zirconia was first observed on the bottom surface of the PVD PSZ after 200 h of isothermal heat treatment. The failure of TBCs occurred either in the bond coat oxidation products of αAl₂O₃ and rutile TiO₂ or at the interface between the oxidation products and the diffusion aluminide bond coat or the PSZ coating.     

基于逆向工程的显像管玻壳模CAD建模

分析了逆向工程(RE)的几个关键技术,包括点云数据的获取、曲面重构和三维建模的方法步骤,逆向工程与其他CAD/CAM系统的数据交换,介绍了模具曲面逆向工程原理、方法及过程,并用实例验证了曲面逆向工程的应用。     

Parameters affecting TGO growth rate and the lifetime of TBC systems with MCrAlY‐bondcoats

In the present work different parameters which affect the oxide growth on MCrAlY‐bondcoats have been studied, in an attempt to find a reliable way to define the critical oxide thickness to failure of an EB‐PVD thermal barrier coatings (TBC). It was found that the variation of selected parameters such as oxidation temperature, surface roughness, and bondcoat thickness certainly alters the thermally grown oxide (TGO) growth rate. However, simultaneously the morphology, composition, and/or microstructure of the oxide are changed, which can affect the critical TGO thickness to failure in a TBC system. In contrast, the variation of the oxygen partial pressure of the oxidizing atmosphere led to different TGO growth rates without significantly changing the oxide morphology and composition. Comparing the TGOs grown at different rates in the specimens exposed to high pO₂ and low pO₂ atmospheres, it was estimated that at failure the oxide scales in both specimens have reached a similar critical thickness.     

Towards Long-Life Replacement Joint Prostheses - A Surface Engineering Approach

TOTAL JOINT ARTHROPLASTY is widely regardedas one of the greatest achievements in the field ofbiomaterials and bioengineering in the last century.However,clinical practices show that most currentjoints prostheses only can last some10-15years mainlydue to the wear of the bearing surfaces and theassociated aseptic loosening,which necessitatesrevision surgery.Indeed,about a quarter of all jointreplacement operations are revisions,which are morecomplex,more expensive and have a higher fail…