Ceramic for gas burner

Hi, I am a senior Mechanical Engineer at San Diego State University. I will be using the ceramic for a gas burner so I\\\'m looking for a ceramic that has a relatively low thermal expansion and a high operating temperature range. I am also looking for a porosity of about 50 percent. I\\\'m looking to buy some for my senior design project, but wanted to get some information about the ceramics you offer. What is the minimum amount I can order? What sizes do you offer? Is the ceramic machinable? How much do they cost?I am looking forward to hearing from you-Thank you.