Method for producing thick ceramic films by a sol gel coating process

a technology of ceramic film and gel coating, which is applied in the direction of liquid/solution decomposition chemical coating, prosthesis, impression caps, etc., can solve the problems of expensive vacuum system, inability to successfully coat and limited technique to line of sight geometries

Inactive Publication Date: 2000-02-15
DATEC COATING CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

An object of the present invention is to provide an improved method for applying adherent ceramic fil...

Problems solved by technology

Another drawback of the plasma spray technique is that only line of sight geometries can be successfully coated.
In PVD, expensive vacuum systems are required to coat high quality ceramic films of less than 10 .mu.m.
In addition this technique is also limited to line of sight geometries.
Clearly a 10 .mu.m film made 0.1 .mu.m at a time is a very time consuming and laborious process.
Sol Gel films are, however, very susceptible to substrate interaction,...

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

PZT Films

In a typical PZT recipe 4 g of lead acetate was dissolved in 6 g of acetic acid. Heating was often required to fully dissolve the Pb(OCOCH.sub.3).sub.2. After the solution was allowed to cool, 4 g of zirconium propoxide, 2 g of titanium isopropoxide, 2.5 g of distilled, deionized water (DDW), 1 g of polyethylene glycol and 1 g of glycerol were added and well mixed. PZT powder (6 g) was then added to the resulting solution and dispersed by ultrasonic mixing.

Films were deposited onto planar substrates by spin coating and subsequently fired at 400.degree. C. Thicker films were achieved by repeating the sequence until the desired thickness was obtained. The films were then heated at 650.degree. C. for 1 hour. Fibres and wires were coated using an automated dipping system.

PZT films deposited onto planar substrates produced crack free films that were 9-60 .mu.m thick. The films were found insulating indicating that they were pinhole free. Under observation by scanning electron mi...

example 2

Zirconia and Titania Films

The development of zirconia and titania films was carried out in two stages. The first stage involved the fabrication of zirconia and titania films without adding inorganic additives to the sol gel solution and the second investigated the use of inorganic additives to improve both the distribution of the particles within the film and its adhesion to substrates.

Titania and zirconia sol gel mixtures were prepared by mixing 4 g of either zirconium propoxide or titanium isopropoxide with 3 g acetic acid, 2 g DDW, 0.5 g polyethylene glycol and 0.5 g glycerol. Either 4 g of yttria partially stabilized zirconia or titania powder was added to the appropriate sol gel solution and the mixture sonified for at least 5 min. The films were then deposited onto aluminium foil and stainless steel coupons by spin coating and firing at 500.degree. C. Films heated above 600.degree. C. tended not to adhere to the substrate and could be rubbed off.

Modified sol gel mixtures were ...

example 3

Modified Zirconia Films on Other Substrates

Modified sol gel dispersions of CSZ and YSZ were either spin or dip coated onto soft steel, stainless steel, Inconel.RTM. and carbon / carbon composite. The dispersions were prepared by dissolving 2 g of calcium nitrate in 4 g of acetic acid. To the resulting solution 8.5 g of zirconium propoxide, 2.5 g DDW and 1 g each of polyethylene glycol and glycerol. Ceramic powder (4 g) was added as before. Coatings on soft steel were fired and heated for at least 8 hours at 500.degree. C. Coatings on stainless steel and Inconel.RTM. were fired at 700.degree. C. and heated for at least 8 hours at 700.degree. C. and 900.degree. C. respectively. Coatings on carbon / carbon composites were fired at 450.degree. C. Rods of carbon steel, stainless steel and inconel were dip coated and fired and heated in a manner similar to the coupons.

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Abstract

A method for producing thick ceramic films of greater than 10 mu m on selected substrates is described. Conventional sol gel solutions are loaded with up to about 90% by weight of finely divided ceramic particles and mixed. The resulting slurry or paint can be either spun or dip coated or sprayed or painted onto a planar or other substrate, fired to remove the organic materials and to develop a microcrystalline structure. The fired film may then be heated. Composite films are also contemplated.

Description

FIELD OF THE INVENTIONThis invention relates to the production of thick ceramic films, including composite films, on selected substrates, using a sol-gel coating technique. More particularly this invention relates to a technique for depositing polycrystalline ceramic films such as lead zirconate titanate and partially stabilized zirconia, in thicknesses greater than 10 .mu.m.BACKGROUND OF THE INVENTIONCeramic coatings can be prepared by thermal or plasma spraying and physical vapour deposition (PVD) techniques. In plasma spray, a bulk powder is passed through a plasma and directed towards a substrate where it cools on contact. Films up to 10 mm thick can be produced in this way but usually need post-deposition heating as the deposited film tends to be porous (10% porosity is considered good). Another drawback of the plasma spray technique is that only line of sight geometries can be successfully coated. In PVD, expensive vacuum systems are required to coat high quality ceramic films...

Claims

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Application Information

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IPC IPC(8): C23C18/12C23C18/00C04B35/622
CPCC04B35/62218C23C18/1208C23C18/1225C23C18/1241C23C18/1254C23C18/1295C04B41/5027C04B41/4537C04B41/4554C04B41/5053C04B41/52C23C18/127C23C18/12
Inventor BARROW, DAVID A.PETROFF, T. EDWARDSAYER, MICHAEL
Owner DATEC COATING CORP
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