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APS Materials – Advances In Medical Ceramic Coatings

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With bone implants, the degree of success is dependent on the extent of osseointegration.  Inducing bone growth into the implant provides a cement-free bond of high strength and durability, allowing optimal mechanical properties.  This has always been the goal with bone implants, and today’s titanium and hydroxyapatite coatings have achieved it more fully than ever before.

The exceptional success of these coatings is partly due to their materials, but can also be credited to the method of application.  When a bone implant is manufactured today, the ceramic coating is applied by a thermal spray process similar to that used to apply acid-resistant coatings to machine parts.

In this process, microscopic particles of the material are passed through the beam of a plasma torch, instantly melting them into droplets to which a positive charge is applied.  The piece to be coated has an attractive charge, so the droplets are applied to the surface in a smooth coating of uniform thickness.  Using this method, even the most convoluted shapes can be thoroughly coated to ensure uniform performance and adhesion to bone.

The same thermal spray technique can ensure better performance and longer life for machine parts such as those used in jet engines.  When these parts fail, it is often due to thermal stress from frequent heating and cooling.  Ceramic coatings can alter the thermal conductivity of metal machine parts, greatly extending their lifespan and ensuring that their strength will remain undiminished for the entire time.

Just as ceramic coatings protect metal parts from excessive heat, they can insulate them from contact with harmful chemicals.  One example of this is in semiconductor manufacturing where etching of silicon wafers is performed by corrosive gases inside a chamber.  A thermally sprayed coating is used to protect the inside of the chamber and its parts from the gases, greatly extending their lifespan.

Ceramic coatings can be used for electrical insulation to prevent metal parts from conducting a current and acquiring a magnetic charge, an important concern with many electrical devices.  When parts come into physical contact with each other, their surfaces can be altered by a ceramic coating to give them a different coefficient of friction.

In each of these applications, the secret to longer life and better performance is the ceramic coating and the way it is applied to alter the object’s physical properties.  Ceramic coatings literally keep the modern world moving.