METHOD FOR IMPROVING RESISTANCE OF CERAMIC PTC THERMAL ELEMENT TO REDUCTION

Abstract

A method for improving the resistance of a ceramic PTC thermal element to reduction is provided, belonging to the technical field of preparation of electronic components. The ceramic PTC thermal element is barium titanate based. The method includes: filling a material container body with the barium titanate based ceramic PTC thermal element; loading the material container body containing the element into a magnetron sputtering apparatus; sputtering, by the magnetron sputtering apparatus, an inorganic material as a target material onto the surface of the element when the material container body is in a rotating state, thereby forming a thin film layer of the inorganic material on the surface; and after the magnetron sputtering is completed, taking out the material container body containing the element with the thin film layer of the inorganic material combined on the surface, and performing high-temperature heat treatment.

Claims

1. A method for improving the resistance of a ceramic positive temperature coefficient (PTC) thermal element to reduction, the ceramic PTC thermal element being a barium titanate based ceramic PTC thermal element, wherein the method for improving the resistance to reduction comprises: filling a material container body with the barium titanate based ceramic PTC thermal element; loading the material container body containing the barium titanate based ceramic PTC thermal element into a magnetron sputtering apparatus; sputtering, by the magnetron sputtering apparatus, an inorganic material as a target material onto the surface of the barium titanate based ceramic PTC thermal element when the material container body is in a rotating state, thereby forming a thin film layer of the inorganic material on the surface for preventing harmful gases from entering ceramic grain boundaries via micropores on the surface of the barium titanate based ceramic PTC thermal element; and after the magnetron sputtering is completed, taking out the material container body containing the barium titanate based ceramic PTC thermal element with the thin film layer of the inorganic material combined on the surface, and performing high-temperature heat treatment while controlling the temperature and time of the high-temperature heat treatment.

2. The method for improving the resistance of a ceramic PTC thermal element to reduction according to claim 1, wherein the inorganic material is any one or a mixture of more than one of ZnO, Al.sub.2O.sub.3, SiO.sub.2, ZrO.sub.2, CaO, SrO, TiO.sub.2, and BaO.

3. The method for improving the resistance of a ceramic PTC thermal element to reduction according to claim 2, wherein when the inorganic material is a mixture of Al.sub.2O.sub.3, SiO.sub.2 and TiO.sub.2, the molar ratio of Al.sub.2O.sub.3:SiO.sub.2:TiO.sub.2 is 1:1:1.

4. The method for improving the resistance of a ceramic PTC thermal element to reduction according to claim 1, wherein the material container body is in a cylindrical shape, holes are formed at intervals around the material container body, an opening and closing door of the material container body is formed on the material container body, and pivot support shafts are formed at the central positions of two end faces of the material container body.

5. The method for improving the resistance of a ceramic PTC thermal element to reduction according to claim 1, wherein the thin film layer of the inorganic material has a thickness of 0.1-3 m.

6. The method for improving the resistance of a ceramic PTC thermal element to reduction according to claim 1, wherein the material container body being in a rotating state refers to the material container body being in a rotating state at a rotational speed of 10-100 rpm.

7. The method for improving the resistance of a ceramic PTC thermal element to reduction according to claim 1, wherein an apparatus used for performing the high-temperature heat treatment is a high-temperature furnace.

8. The method for improving the resistance of a ceramic PTC thermal element to reduction according to claim 1, wherein the controlling the temperature of the high-temperature heat treatment is to control the temperature of the high-temperature heat treatment to 300-500 C.; and the controlling the time of the high-temperature heat treatment is to control the time of the high-temperature heat treatment to 30-60 min.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] FIG. 1 is a schematic diagram of a material container used in the present disclosure.

[0016] In the FIGURE: 1, material container body; 2, pivot support shaft; and 3, barium titanate based ceramic PTC thermal element.

DETAILED DESCRIPTION

Example 1

[0017] The present disclosure provides a method for improving the resistance of a ceramic PTC thermal element to reduction. The ceramic PTC thermal element is a barium titanate based ceramic PTC thermal element. The method for improving the resistance to reduction is described below. A cylindrical material container body 1 as shown in FIG. 1 is filled with the barium titanate based ceramic PTC thermal element 3. Holes are formed at intervals around the surface of the material container body 1. The size or diameter of the holes should be as large as possible as long as the barium titanate based ceramic PTC thermal element 3 cannot be thrown out, that is to say, the diameter of the holes is slightly smaller than the diameter of the barium titanate based ceramic PTC thermal element 3. An opening and closing door of the material container body is formed on the material container body 1, and pivot support shafts 2 are formed at the central positions of two ends of the material container body 1. Then, the cylindrical material container body 1 containing the barium titanate based ceramic PTC thermal element 3 is loaded into magnetron sputtering apparatus, i.e., a magnetron sputtering machine. When the cylindrical material container body 1 is in a rotating state of 100 rpm, that is, at a rotational speed of 100 rpm, an inorganic material as the target material is sputtered onto the surface of the barium titanate based ceramic PTC thermal element 3 by the magnetron sputtering apparatus, thereby forming a 0.1 m thick thin film layer of the inorganic material on the surface to prevent harmful gases from entering ceramic grain boundaries via micropores on the surface of the barium titanate based ceramic PTC thermal element 3, that is, the thickness of the thin film layer of the inorganic material is 0.1 m. After the magnetron sputtering is completed, the material container body 1 containing the barium titanate based ceramic PTC thermal element 3 with the thin film layer of the inorganic material combined on the surface is taken out and loaded into a high-temperature furnace for high-temperature heat treatment at 500 C. for 30 min. In the present example, the inorganic material is a mixture of Al.sub.2O.sub.3, SiO.sub.2 and TiO.sub.2 mixed in a molar ratio of 1:1:1.

Example 2

[0018] The inorganic material is changed to TiO.sub.2. The temperature and time of the high-temperature heat treatment are changed to 300 C. and 60 min, respectively. The rotational speed of the cylindrical material container body 1 is changed to 10 rpm. The thickness of the thin film layer of the inorganic material is changed to 3 m. The rest are the same as the description of Example 1.

Example 3

[0019] The inorganic material is changed to a mixture of ZnO, SiO.sub.2, ZrO.sub.2, SrO and BaO mixed in an equal molar ratio or random molar ratio. The temperature and time of the high-temperature heat treatment are changed to 400 C. and 45 min, respectively. The rotational speed of the cylindrical material container body 1 is changed to 60 rpm. The thickness of the thin film layer of the inorganic material is changed to 1.6 m. The rest are the same as the description of Example 1.