Patent ID: 7845546
Filing Date: 2010-12-07
Classification: C04B,G01L,Y10T

Abstract:
1. A method for the production of a vacuum measuring cell ( 8 ) for measuring a medium, the vacuum measuring cell comprising first and second housing plates ( 1 , 4 ) and a diaphragm ( 2 ) for functioning as a pressure transducer, one side of the diaphragm ( 2 ) being spaced apart from a portion of the first housing plate ( 1 ) around a margin region of the first housing plate that is engaged against a margin region of the diaphragm in a first joining region by joining means ( 3 ) forming a seal, so that between the margin regions of the first housing plate and the diaphragm, a reference vacuum chamber ( 7 ) is formed, an opposite side of the diaphragm ( 2 ) being spaced apart from a portion of the second housing plate ( 4 ) around a margin region of the second housing plate that is engaged against the margin region of the diaphragm in a second joining region by joining means ( 3 ) forming a seal, so that between the margin region of the second housing plate and the diaphragm, a measuring vacuum chamber ( 9 ) is formed, the second housing plate ( 4 ) including an opening for communicating the measuring vacuum chamber ( 9 ) to the medium, the vacuum measuring cell including connection means ( 5 ) with joining means ( 6 ) connected to the second housing part for forming a seal for joining the measuring vacuum chamber ( 9 ) with the medium to be measured in a third joining region, wherein at least the diaphragm ( 2 ) and the two housing plates ( 1 , 4 ) are ceramic parts ( 1 , 2 , 4 ) of an aluminum oxide, the method comprising: forming at least one of the joining means ( 3 , 6 ) of metallic aluminum having a thickness in the range of 0.5 μm to 30 μm; disposing the at least one joining means in one of the joining regions between the ceramic parts ( 1 , 2 , 4 ); and joining the ceramic parts by pressing the ceramic parts ( 1 , 2 , 4 ) to be joined together at increased temperature in the range of 600° C. to 680° C. in a process gas atmosphere encompassing the parts to be joined, the process gas atmosphere including a reducing gas, and the pressing occurring during a time in the range of 30 to 90 minutes; and subsequently to the pressing step, performing a tempering step in a second process gas atmosphere which includes oxygen, wherein the tempering step takes place in a temperature range of 450° C. to 575° C. so that the metallic aluminum is substantially oxidized to aluminum oxide.