Ceramic substrate for receiving resistive film and method of forming chromium/chromium oxide ceramic substrate

• US 3,916,071 A
• Filed: 11/05/1973
• Issued: 10/28/1975
• Est. Priority Date: 11/05/1973
• Status: Expired due to Term

• Current Assignee: Elmer A. Wolff Jr, Gerald P. Kinnebrew, James O. Redwanz
• Original Assignee: Elmer A. Wolff Jr, Gerald P. Kinnebrew, James O. Redwanz
• Inventors: Redwanz, James O., Kinnebrew, Gerald P., Wolff, Elmer A. Jr.
• Primary Examiner(s): Weiffenbach, Cameron K.
• Application Number:
  US05/412,938
• Time in Patent Office: 722 Days
• Field of Search: 117/215,217 338/308,300,302,314 252/512,518 427/103,123,126 428/376,377,378,381,384,389,398,399,472
• US Class Current: 428/376
• CPC Class Codes: C23C 14/0021 Reactive sputtering or evaporation
• CPC Class Codes: C23C 14/22 characterised by the process of coating
• CPC Class Codes: C23C 14/223 specially adapted for coating particles
• CPC Class Codes: H01C 17/08 by vapour deposition
• CPC Class Codes: H01C 7/18 comprising a plurality of layers stacked between terminals
• CPC Class Codes: Y10T 428/2935 Discontinuous or tubular or cellular core
• CPC Class Codes: Y10T 428/2936 Wound or wrapped core or coating [i.e., spiral or helical]
• CPC Class Codes: Y10T 428/2938 Coating on discrete and individual rods, strands or filaments
• CPC Class Codes: Y10T 428/2944 Free metal in coating
• CPC Class Codes: Y10T 428/2949 Glass, ceramic or metal oxide in coating
• CPC Class Codes: Y10T 428/2958 Metal or metal compound in coating
• CPC Class Codes: Y10T 428/2975 Tubular or cellular
• CPC Class Codes: Y10T 428/2976 Longitudinally varying

Abstract

The disclosure relates to a method of forming a resistive film on a substrate formed of a metal having a coating of a ceramic oxide of the metal by the controlled heating and/or application of oxygen to the film producing system. Chromium is heated in a reduced pressure air atmosphere, containing the normal ratio of oxygen found in air, to a temperature at which the chromium will atomize. The chromium, which is electrically conductive and has a positive temperature coefficient of resistance, along with a chromium sub-oxide which is somewhat electrically conductive and has a negative temperature coefficient of resistance will deposit on ceramic substrates which are being continually rotated within a tumbler or the like within the partially evacuated system. The chromium sub-oxide along with small amounts of chromium will deposit on the ceramic with the ratio of chromium sub-oxide to chromium metal continually changing in favor of the metal as the oxygen in the atmosphere is used up. At a more elevated temperature, mainly chromium will deposit as the metal on the ceramic substrate after the oxygen has been substantially depleted. The amount of chromium metal deposited on the substrate is controlled by the temperature to which the chromium is heated as well as the length of time at which the chromium is above the temperature required for deposition thereof onto the ceramic substrate. In accordance with another embodiment, the amount of oxygen in the evacuated area can be controlled from an external source to control the amount of chromium sub-oxide which can be deposited upon the ceramic substrate. Also disclosed is the meta substrate having the ceramic oxide of the metal thereon. Aluminum with an anodized outer surface is specifically set forth. In addition, a flexible ceramic substrate is disclosed for use in the procedure for forming resistive coatings.

Claims

1. A RESISTIVE DEVICE WHICH COMPRISES:

A. A METAL BASE, THE OXIDE OF SAID METAL BEING A CERAMIC MATERIAL, B. A COATING OF THE OXIDE OF SAID METAL ON SAID METAL, AND

2. A resistive device as set forth in claim 1 wherein said resistive film comprises plural layers, each layer having a different ratio of chromium to chromium oxide.

3. A resistive device as set forth in claim 1 wherein said base is cylindrical in shape and said resistive film is in the form of a helix on said coating.

4. A resistive device as set forth in claim 3 wherein said resistive film comprises plural layers, each layer having a different ratio of chromium to chromium oxide.

5. A resistive device as set forth in claim 1 wherein said metal is aluminum and said oxide is aluminum oxide.

6. A resistive device as set forth in claim 5 wherein said resistive film comprises plural layers, each layer having a different ratio of chromium to chromium oxide.

7. A resistive device as set forth in claim 5 wherein said base is cylindrical in shape and said resistive film is in the form of a helix on said coating.

8. A resistive device as set forth in claim 7 having plural resistive layers wherein each of said layers has a different chromium to chromium oxide ratio.