Chemically Resistant Multilayered Coating for a Measuring Device Used in Process Engineering
A field device used in process and/or automation engineering for monitoring at least one chemical or physical process variable of a medium in a component carrying a medium at least partially and temporarily and comprising at least an electronic unit and a sensor unit. At least one portion of at least one component of the sensor unit is in contact with the medium at least temporarily. The at least one portion of the component in contact with the medium is provided with a chemically resistant multilayered coating consisting of at least two layers, wherein a first layer is made of a material consisting of a densely packed atomic arrangement which provides a protection against corrosion by said medium, and a second layer consisting of a chemically resistant plastic material is arranged around the first layer and protects the first layer against outer damage and corrosion.
1 - 12 . (canceled)
13 . A field device used in process and/or automation engineering for monitoring at least one chemical or physical process variable of a medium in a component carrying a medium at least partially and temporarily, comprising:
at least an electronics unit; and
a sensor unit, wherein:
at least one portion of at least one component of said sensor unit is in contact with the medium at least temporarily;
at least the portion of said component in contact with the medium is provided with a chemically resistant multilayered coating consisting of at least two layers, wherein a first layer is made of a material consisting of a densely packed atomic arrangement and provides a protection against corrosion by said medium, wherein a second layer consisting of a chemically resistant plastic material is arranged around said first layer and protects the first layer against external damage and corrosion.
14 . The field device according to claim 13 , wherein:
said second layer consists of PFA, PTFE, FEP, ECTFE, PEEK, or rubber.
15 . The field device according to claim 13 , wherein:
said first layer consists of a metal—in particular, gold, platinum, silver, or tantalum—SiC, DLC, Al 2 O3, SiO 2 , or BN.
16 . The field device according to claim 13 , wherein:
an elastic material—in particular, SiC or DLC, or a two-layer system made of SiC and DLC—is used for said first layer.
17 . The field device according to claim 13 , wherein:
said first layer is produced using a galvanic deposition process.
18 . The field device according to claim 13 , wherein:
said first layer is produced using a CVD method—in particular, using a CVD method in plasma under low temperature conditions.
19 . The field device according to claim 13 , wherein:
said first layer is produced using a sol-gel method.
20 . The field device according to claim 19 , wherein:
the surface energy of said first layer in the portion facing the medium is suitably adjusted—in particular, maximized—particularly by oxidation or doping.
21 . The field device according to claim 20 , wherein:
said first layer is a hybrid structure.
22 . The field device according to claim 13 , wherein:
the field device is a pressure-measuring cell; and
said component in contact with the medium at least in one portion and at least partially is a membrane.
23 . The field device according to claim 21 , wherein:
said first layer has a thickness of about 10 μm and is elastic; and
said second layer ( 5 ) has a thickness of about 300 μm.
24 . The field device according to claim 13 , wherein:
the field device is a fill state measuring device, and said sensor unit has a unit capable of oscillating which is said component in contact with the medium at least in one portion and at least partially, and which is provided in the portion facing the medium with a multilayered coating.