Material: 95% alumina Specification： A: Wave Tube：(UNIT:MM)： 1.Φ240X200 2.Φ150X200 3.Φ140X183 4.Φ125X183 5.Φ110X183 6.Φ103X183 7.Φ102X183 8.Φ98X96 9.Φ80X165 10.Φ75X165 11.Φ75X149 12.Φ75X120 13.Φ68X125 B: Straight Tube: (UNIT: MM): 1.Φ250X500 2.Φ160X200 3.Φ155X183 4.Φ152.4X14 5.Φ150X183 6.Φ140X183 7.Φ110X183 8.Φ103X183 9.Φ100X100 10.Φ90X65 11.Φ82X120 12.Φ82X100 13.Φ60X120 Perfomance volumn density ≥3.6g/cm3 bending strength ≥275MPa breakdown voltage ＞15KV/mm dielectric constant 1MHz 20°C 9～10 volumn resistance ＞1013Ω?cm coefficient of linear expansion 6.5～8?10-6mm/°C dielectric loss tange at 1MHz 20 °C ＜3.5?10-4 Heat and shock resistance Pass metallization tensile strength ≥90MPa Practise：This kind of ceramic crust is a main parts of high voltage electronic vacuum switch, contactor, X-ray tube, thyratron and high power ultra-high frequency emission tube in power and electronic industries, etc.