Sheathed thermocouple high-temperature brazing protective agent and preparation method thereof

Abstract

The invention discloses a sheathed thermocouple high-temperature brazing protective agent which comprises the following components in parts by weight: 5-9 parts of magnesium oxide powder, 1 part of polyvinyl alcohol and 40-80 parts of deionized water. The invention further provides a preparation method of the protective agent. The protective agent disclosed by the invention is high in viscosity, a liquid-state protective agent can be adsorbed at a high temperature, the spread range of the protective agent is controlled, the protective agent is prevented from intruding weld joints, and the condition that thermo wires are polluted is avoided. The protective agent has a porous structure, the cooled protective agent can be adsorbed to the protective agent, the protective agent is prevented from being crystallized on the welded part and then is conveniently removed, the residue condition of the protective agent is improved, and hazards such as corrosion and moisture absorption caused by residues of the protective agent are eliminated. The magnesium oxide powder in the protective agent is homologous to a principal material of a sheathed thermocouple, and thus bad effects caused to the coating part are avoided. The protective agent is low in density and high in adhesion degree, is suitable to be coated at each position and does not drop in a high-temperature state, and thus effective brazing is guaranteed. The protective agent is low in raw material cost, convenient to prepare and wide in application range.

Description

technical field [0001] The invention relates to a brazing protective agent, in particular to an armored thermocouple high-temperature brazing protective agent and a preparation method thereof. Background technique [0002] In the sensor products, there are a large number of fixed structures in which the casing and the armored couple, the armored couple and the armored couple, and the armored couple and the mounting seat are connected and fixed. These joints are generally connected by brazing, and the weld requires not only strength and airtightness, it also needs to be able to serve for a long time in a high temperature environment. According to the different types of sensors, the service environment temperature of the welds ranges from 30°C to 800°C, so such welds are usually brazed (the solder has a high melting point In addition, it is necessary to control the distribution range of the solder and the flow distribution area of ​​the flux during brazing to ensure the consis...

AI Technical Summary

Problems solved by technology

Another way to remove the oxide film is to use flux. After heating, the flux will become molten and cover the part to be welded to mechanically isolate it from the environment. However, the flux in the molten state will flow to the weld. Internal penetration, when encountering a through weld, the flux will seep out of the bottom, sometimes polluting the even wire, difficult to remove, leaving hidden dangers