Recommendations are given for coating high- strength, low-alloy steels by ceramics. Ceramics considered are from all walks of life (medical profession to chemical industry). This broad perspective is necessary in order to find solutions to such a challenging problem. Ceramics are selected based on their physical compatibly to a steel termination end. Candidate ceramics are cobalt oxide, entatite, fosterite, nickel oxide, zirconia, silica-zirconia, porcelain enamels, silicates, EE1087, Incon 713, and modified alumina. Coating process must yield a ceramic coating that (1) adheres to steel for a minimum of four to six months, (2) has low porosity (<5%) so that the dense layer acts as an electrical and electrolytic barrier to sea water, (3) has no macrocracks, (4) withstands service temperature of 0-150µC (32-302µF), (4) withstands stresses associated with winding process, (5) withstands service stresses like axial tension, axial compression, high binding moments, and (6) has a rough surface. Coating processes selected to lay-down the ceramic are plasma-spraying with LASER or resin, and air- brush spraying with heat-treatment. These processes have been used in the past, meeting previously stated requirements.
Aside from the original objective of the work, interesting information has been uncovered about protecting drill-pipe and drill-collars from abrasive mud via ceramic coating. Wear resistant coatings may be provided via plasma-spraying and PulsFusion Surfacing (see Chapter 3).
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