In the past six months, this project was focused on more fundamental studies of the coating properties. The properties of each individual coating TiB{sub 2}, TiBC as well as the alternating TiB{sub 2}/TiBC laminates were studied. These properties include residual stress, surface morphology and topography, adhesion and wear rate. The coatings were deposited using dc magnetron reactive sputtering process. Deposition of the films was carried out in a production-scale, three-chamber-in-line coating system, consisting of a load-lock chamber, and two deposition chambers. The substrates were cleaned and mounted on a rack before going into the chamber. A computerized conveyor system transported the rack into the load-lock chamber, where the pressure was pumped down to around 2E-5 torr. The substrates were then preheated by an infrared heater to about 100 C. After preheating, the substrates were transported into the first deposition chamber through a gate valve. The base pressure of the deposition chambers is 2E-6 torr. A layer of Ti was deposited on the substrates using two 5 inch x 20 inch Ti targets in the first deposition chamber as the adhesion layer. The substrates were then transported to the second deposition chamber for the TiB{sub 2} and Ti-B-C-N depositions. In the second deposition chamber, two 5 inch x 20 inch TiB{sub 2} targets were mounted on both sides. For the TiB{sub 2} deposition, argon was introduced into the chamber. For the Ti-B-C-N deposition, acetylene and nitrogen were introduced into the chamber through four gas distribution manifolds to insure the uniformity. The partial pressure of the reactive gases were controlled by a PID control loop. Substrate bias is one of the key deposition parameters. Bias voltages ranged from 40 to 300V. Current density is around 2 mA/cm{sup 2}. The deposition rate is about 1.5 {micro}m/hr. All the test coatings, used for thickness and hardness measurement, as well as, microstructural studies, were deposited on polished 001 silicon wafers. All the coatings used for wear tests, were deposited on polished 1 inch stainless steel 316 disks.
