| The objective of this research is to investigate the properties and machining characteristics of Polymer Bonded Ceramic (PBC) green bodies, a new class of materials, based on silica and alumina. One type of epoxy will be used as a polymer constituent. For each type of ceramic material, there are two types of PBC, according to the fabrication method employed. The first one is called Polymer Bonded Ceramic - Compacted (PBCC); where the ceramic matrices are compacted along with the polymer. The second type is Polymer Bonded Ceramic - Presintered (PBCP); where the ceramic matrices are presintered and the polymer is infiltrated into the body. There is at least 80% (by weight) ceramic with up to 20% (by weight) polymer added to strengthen and toughen the material.;The fabrication methods were evaluated, and physical and mechanical properties of PBCCs and PBCPs were tested. Successfully fabricated parts were investigated for machining characteristics using conventional milling. Statistical tests were performed to evaluate the properties and machining characteristics of the materials.;It was found that alumina has superior wettability with the polymer utilized in the research. The compaction process resulted in no polymer extrusion through the die. The presintering and polymer infiltration processes were successful. There is an indication that the compaction method produced better results in density, hardness, compressive strength, and surface finish for better wettability ceramic powders (alumina). However, the presintering method seemed to produce better results, in the same categories as above, for poor wettability ceramic powders (silica).;The areas of greatest concern are low values of hardness, and compressive strength for the PBCs. In addition, high wear of cobalt tooling, variability of cutting forces using carbide tooling, and variability of the machine tools themselves are also of some concerns. The samples subjected to post processing all cracked.;This research adds to the knowledge of machining of green bodies. The PBCs were clearly machinable. Tooling requirements, process parameters, fixture design and machine tool protection techniques are suggested. This comprehensive study opens further possibilities and establishes new parameters for green body machining. |
