Friday, March 4, 2011

Sezgin Koçak - 030070026 - Fourth Week

Electropolishing:

Electropolishing is a electrochemical process by which surface material is removed by anodic dissolution. Sometimes referred to as reverse plating, electropolishing actually removes surface material beginning with high points within the microscopic surface texture. By removing these points, the electropolishing process will improve the surface finish, leaving a smoother and more reflective surface. Electropolishing delivers a smoother, more reflective surface that reduces product adhesion and imporves surface cleanability. This porcess improves the near surface chemistry of the material, and promotes to the formation of an improved corrosion-resistant surface layer.

(O. G. Palana, Engineering Chemistry, p.162)

Vitreous Coatings:

Vitreous coatings are smooth,nonpourus, bonded coatings that are resistant to temperatures up to 1800F for long periods. High temperature vitreous or glass refractory coatings are applied superalloy substrates by using modifications of existing enameleing materials. Improvements in vitreous coatings are made by adding refractory oxides to the basic formulation. This results in "matte" finish coatings that can protect from temperatures reaching 2200F. Ussually several layers of coating are built up on the substrate surface by additional coating-firing operations.

(National Research Council (US) Comitee on Coatings, High-temperature oxidation-resistant coatings, p 64-65)

Powder Spray (coating):

There are two principals application methods for powder coatings: spraying and fluidized bed. In the spraying method, an electrostatic charge is given to each particle in order to attract it to an electrically grounded part surface. Several spray gun designs are available to impart the charge to the powders. The spray guns cab ne operated manually or by industrial robots. Compressed air is used to propel the powders to the nozzle. The powders are dry when sprayed, and any excess particles that do not attach to the surface can be recycled (unless multiple paint colors are mixed in the same spray booth). Powders can be sprayed onto a part at room temperature, followed by heating of the part to the melt the powders; or they can be sprayed onto a part that has been heated to the above the melting point of the powder, which usually provides a thicker coating.

(M.P. Groover, Fundamentals of modern manufacturing, 3rd edition, p.349)

Holography:

The term "holography" is a compound of the Greek words "holos=complete" and "graphein=to write". It denotes a procedure for three dimensional recording and displaying of images and information without the use of lenses. Therefore holography opens up completely new possibilities in science, engineering, graphics and arts. Fields of application are interferometric measurements techniques, image processing, holographic optical elements and memories as well as part holograms. Holography uses the properties interference and diffraction of light which make it possible to reconstruct the object wave completely. To be able to see these effects coherent laser light has to be used. "Coherence" means that the light wave is constant and contiguous.

(G. Ackermann,J. Eichler, Holography: a practical approach, p.4-5)

2 comments:

  1. sezgin, Thermal Shock kelimesini selçuk tevruz önceden girmiş. değiştiriver sıkıntı olmasın dostum.

    ReplyDelete
  2. aslında arkadasımız biraz hile yaptı ama yine de ben değistireyim. Eyvallah abi, sağol uyardığın için

    ReplyDelete