Fabrication of porous alumina using a paraffin pore-forming agent for laser pump cavity applications

Abstract

Paraffin was employed as a pore-forming agent to achieve porous alumina. Trichloroethylene, toluene, and chloroform were utilized for dissolving paraffin to explore the impact of the solvent on the properties of porous alumina. The influence of the paraffin ratio (1, 3, 5, and 7 wt%) was also examined on the properties of porous alumina. The samples were compacted under different pressures ranging from 30 to 50 MPa. The samples were then sintered at 1400 °C. The density of the samples was examined by the Archimedes method. The porosity percentage depended on the content of the pore-forming agent and the initial pressure of the compaction process. Based on the X-ray diffraction results, the size of the crystallites was about 230 nm. The sample with 3 wt% paraffin showed the highest strength (155 MPa) which can be assigned to its proper pore size distribution. The distribution and size of the pores were investigated by a field emission scanning electron microscope. Finally, the sample prepared with 5 wt% paraffin in toluene and compacted at 40 MPa was utilized as a laser pump reflector in an Nd-YAG laser cavity. Based on the results, the reflection of the porous alumina was above 99% at the wavelength of 430 nm.