EXPERIMENTAL-DESIGN APPROACH TO DEVELOPMENT OF A CVD ZRN COATING

A design of experiments (DOE) approach has been used for the study of CVD ZrN coatings on cemented carbide substrates. DOE maximizes informa tion gained from a set of experiments through statistical methods of d esign and analysis. A full factorial matrix of twenty experiments was designed using the variables (A) pressure, (B) temperature, (C) H-2/Zr Cl4 and (D) N-2/ZrCl4. Pressure ranged from 100 to 300 torr, temperatu re from 900 to 1050 degrees C, H-2/ZrCl4 from 20 to 60 and N-2/ZrCl4 f rom 5 to 25. The response for deposition rate is compared with theoret ical prediction based on thermodynamic modeling of the system. A norma l probability distribution was used to identify the variables that had a significant effect on deposition rate. These were found to be (B) t emperature and (C) H-2/ZrCl4. Interaction plots for (B) and (C) genera ted by the software clearly show this effect These results are in agre ement with the thermodynamic analysis and are similar to results for T iN coating. Other responses such as color, surface morphology, texture , adhesion and friction are reported.