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A thin-film technology that features an advanced sol-gel process allows cost-effective fabrication of dense, adherent ceramic coatings up to 300 microns thick on metal substrates. By contrast, the conventional sol-gel method produces films that are limited to thicknesses of less than one micron. The new process is being used for industrial applications that are beyond the scope of traditional deposition techniques. These include automotive and aerospace components, electrical insulation, material handling parts, and orthopedic implants.
This article describes the Datec solgel ceramic coating method, compares it with the conventional sol-gel process, and provides examples of applications.
Sol-gel techniques
To make conventional sol-gel films, metal-organic compounds are dissolved in a suitable solvent. Small amounts of other chemicals may be added to control viscosity and surface tension. The result is a colloidal dispersion known as a sol, in which nanometer-size particles are suspended in solution. The solution is then hydrolyzed and stirred. As stirring continues, the solution becomes progressively more viscous. At a definite point called the sol-gel transition, the particles coalesce to form an elastic gel, which is made up of polymers or macroclusters.
To apply the coating, the substrate...