Introduction Surface Engineering By Israa Faisal University of Al-Qadisiyah College of Engineering Material Engineering Department

Introduction SURFACE ENGINEERING Definition: Modification of near-surface structure, chemistry or property of a substrate in order to achieve superior performance and/or durability. It is an enabling technology and can impact a wide range of industrial sectors..

Introduction The desired properties or characteristics of surface-engineered components include: • Improved corrosion resistance through barrier or sacrificial protection • Improved oxidation and/or sulfidation resistance • Improved wear resistance • Reduced frictional energy losses • Improved mechanical properties, for example, enhanced fatigue or toughness • Improved electronic or electrical properties • Improved thermal insulation • Improved aesthetic appearance

Introduction -Combining chemistry, physics, and mechanical engineering with metallurgy and materials science, it contributes to virtually all engineering disciplines. - It can be done on a given surface by metallurgical, mechanical, physical, and chemical means, or by producing a thick layer or a thin coating. - Both metallic and non-metallic surfaces can be engineered to provide improved property or performance.

ADVANTAGES OF SURFACE ENGINEERING Surface engineering has significant role to play in our day-to-day lives as it has led to: The possibility of producing tools, machine components and whole appliances from the materials with lower properties, usually cheaper, and giving their surface improved characteristics. Improvement of reliability of work of tools, machine components and appliances and reduction of failures. Reduction of frequency of replacing used tools and machine parts, as well as frequency of maintenance overhauls. Reduction by 15 to 35% of losses due to corrosion. Minimization of environmental pollution, primarily due to reduction of energy consumption .

CLASSIFICATION OF SURFACE ENGINEERING Adding a Surface Layer or Coating This involves addition of new layer on metal substrate i.e. application of coating or lining. A wide range of processes are used to deposit metal/ceramic and Organic (paints or plastic and rubber coating). Coating methods commonly used are: Organic and Ceramic coatings and lining Hot dip metallic coatings Electroplating (metal or composite coating) Cladding (thick metal coating) Thermal spraying (metal, plastic, ceramic, or composite coatings) Chemical vapor deposition (metals, graphite, diamond, iamondlike carbon, and ceramics) Physical vapor deposition (metals, ceramics, or solid lubricants) Thermoreactive deposition/diffusion process (carbides, nitrides, or carbonitrides)

() Changing the Surface Metallurgy: None of these process changes the surface chemistry, but they improve properties like wear and fatigue by changing surface metallurgy.In this section, surface hardening is limited to localized heat treating processes that produce a hard quenched surface without introducing additional alloying species. a) Localized surface hardening (flame, induction, laser, and electron-beam hardening): Improves wear resistance through the development of a hard martensitic surface. b) Laser melting: Improves wear resistance through grain refinement and the formation of fine dispersions of precipitates on the surface.

() Changing the Surface Chemistry Surface modification that change the surface chemistry of a metal or alloy, but that do not involve intentional buildup or increase in part dimension, include: The process includes: (a) Chemical or electrochemical conversion treatment that produce complex phosphates, chromates/oxides on metal surface. (b) Thermo chemical diffusion heat treatment that involves the introduction of interstitial elements like C, N or B into ferrous alloy surface at elevated temperature. (c) Pack cementation diffusion treatments that involve the introduction of aluminium(Al), Cr or silicon(Si) into alloy surface. (d) Surface modification by ion implantation, which involves introduction of ionized species (virtually any element) into the substrate using ion beam of high velocity electrons. (e) Surface modification by combination of laser beam melting and alloying.

Class  /Organic Coatings Painting and the application of various organic (plastic and rubber) coatings and linings are among the most widely used surface-engineering processes. Paints or linings that act as protective film to isolate the substrate from the environment exist in a number of different forms. Sheet linings, commonly of the vinyl or vinylidene chloride family, are one such type of coating that can be either adhered to the surface to be protected or suspended as a bag within a tank.

Organic Coatings/ Powder coatings Powder coatings are being increasingly used to protect concrete-reinforcing rod, as pipeline coatings, and as coating materials in the original equipment manufacturing markets. Fine powders produced from high-molecular- weight resins of the thermoplastic vinyl and fluorinated hydrocarbon families or from thermoset resins of the epoxy and polyester families are applied to the surface to be protected by either electrostatic spray or fluidized-bed deposition. The metal being protected is usually preheated at the time of application, and after application it is reheated to an elevated temperature (generally from 150-315 0C, or 300-600 0F).

Organic Coatings/ paints the most commonly used organic materials are the liquid-applied (usually by brush, roller, or spray) coating and lining materials, that is, paints. Liquid- applied organic coatings have four basic components: a resin, a solvent, pigments, and other miscellaneous compounds. The resins, often called binders, are dentified by their generic type. These are based on the organic compound structure that makes up the resin. The solvent can be either water or an organic solvent.