Electrophoretic deposition of PEEK/bioactive glass composite coatings for orthopedic implants: A design of experiments (DoE) study

This paper presents a study on the Design of Experiments (DoE) approach to optimize the electrophoretic deposition (EPD) process parameters for PEEK base coatings. PEEK and bioactive glass (45S5 BG) particles were suspended in ethanol and suspensions were stabilized with the help of citric acid. Electric field related parameters were optimized by using Taguchi DoE; an orthogonal array of L15 type with mixed levels of the control factors. Statistical tools were employed to identify the significant factors affecting deposition rate and to quantify the reproducibility of the constant voltage EPD process. It was demonstrated that both deposition voltage and time significantly influence deposition rate. Moreover, statistical confidence was elucidated by Defect Per Million Opportunities (DPMO) model, as proposed in six sigma tools. A pronounced deposition rate was obtained at 100 V/cm in comparison to 110 V/cm, although the adhesion strength and microstructural homogeneity were lower for 100 V/cm. The optimal suspension composition and EPD conditions predicted by DoE were further verified by experiments and qualitative agreement was found between the predicted and experimental data. The experimental results and statistical analyses are discussed based on current knowledge of the EPD of ceramic materials and their co-deposition with polymeric particles.