Surface engineering

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Surface engineering is the sub-discipline of materials science which deals with the surface of solid matter. It has applications to chemistry, mechanical engineering, and electrical engineering (particularly in relation to semiconductor manufacturing).

Solids are composed of a bulk material covered by a surface. The surface which bounds the bulk material is called the Surface Phase. It acts as an interface to the surrounding environment. The bulk material in a solid is called the Bulk Phase.

The surface phase of a solid interacts with the surrounding environment. This interaction can degrade the surface phase over time. Environmental degradation of the surface phase over time can be caused by wear, corrosion, fatigue & creep.

Surface engineering involves altering the properties of the Surface Phase in order to reduce the degradation over time. This is accomplished by making the surface robust to the environment in which it will be used.

Surface Engineering Methods

Surface engineering to enhance resistance to wear, can be accomplished by either altering the properties of the surface or by applying a coating to the surface. Photolithography is a combination of chemical, optical, and mechanical methods to build small structures on a surface.

Altering Surface Properties

Various techniques can be used to enhance the surface properties of a solid. Some options include:

  • Thermal treatments for case hardening
  • Diffusion of Carbon and/ or Nitrogen in steels & hardening the surface
  • Diffusion of Chromium and Aluminum in steel
  • Implanting Nitrogen and/ or Boron ions in steel
  • Peening (thermal process) can be performed either mechanically or with lasers
  • Plasma etching

Surface Coating

Various thermal, athermal, chemical and electrochemical coating processes can be used to reduce the rate of surface phase wear over time. Some processes include:

Applications and Future of Surface Engineering

Surface engineering techniques are being used in the automotive, aerospace, missile, power, electronic, biomedical , textile, petroleum, petrochemical, chemical, steel, power, cement, machine tools, construction industries. Surface engineering techniques can be used to develop a wide range of functional properties, including physical, chemical, electrical, electronic, magnetic, mechanical, wear-resistant and corrosion-resistant properties at the required substrate surfaces. Almost all types of materials, including metals, ceramics, polymers, and composites can be coated on similar or dissimilar materials. It is also possible to form coatings of newer materials (e.g., met glass. beta-C3N4), graded deposits, multi-component deposits etc.

In 1995, surface engineering was a ₤10 billion market in the United Kingdom. Coatings, to make surface life robust from wear and corrosion, was approximately half the market.

In recent years, there has been a paradigm shift in surface engineering from age-old electroplating to processes such as vapor phase deposition, diffusion, thermal spray & welding using advanced heat sources like plasma, laser, ion, electron, microwave, solar beams, pulsed arc, pulsed combustion, spark, friction and induction.

It's estimated that loss due to wear and corrosion in the US is approximately $500 billion. In the US, there are around 9524 establishments (including automotive, aircraft, power and construction industries) who depend on engineered surfaces with support from 23,466 industries.

There are around 65 academic institutions world-wide engaged in surface engineering research and education.

References

  • R.Chattopadhyay, ’Advanced Thermally Assisted Surface Engineering Processes’ Kluwer Academic Publishers, MA, USA (now Springer, NY), 2004, ISBN 1-4020-7696-7, E-ISBN 1-4020-7764-5.
  • R Chattopadhyay, ’Surface Wear- Analysis, Treatment, & Prevention’, ASM-International, Materials Park, OH, USA, 2001, ISBN 0-87170-702-0.

See also

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