Modeling and Experimental Studies of Densification Rates in Current Activated Densification

Current Activated Pressure Assisted Densification (CAPAD) has emerged as one of the most promising methods of materials processing in recent years. This process involves the use of large currents to generate heat coupled with applied pressure in what has proven to be a very powerful powder consolidation technique. Despite intensive research, there is still much to learn about the intricacies of how this process works. In the first part of this work, three material systems, yttria stabilized zirconia, Si, and Al, were processed using the CAPAD technique in order to see how processing conditions affect the densification rates in the CAPAD process. It was found that all materials show a peak densification rate at a particular homologous temperature, which is discussed in terms of material bond type. Pressure was found to directly affect the magnitude of the maximum densification rate in all samples. In the second part of this study, a model was developed to estimate the density-temperature relationship in the CAPAD process. This model is dependent on two parameters that are linked to physical quantities. Experimental data for oxide ceramic materials was used to demonstrate the fitting capability of the model. Oxides were chosen because of the abundance of experimental data available in the literature. Estimating the dominant parameter can be done by finding a material system's activation energy for diffusion and comparing it to other known materials. Guidelines were given on how future CAPAD workers can use the model to save time and resources.