Electric heating tube made of hexagonal boron nitride and mixed heat conducting material thereof

Abstract

The invention belongs to the technical field of electric heating tube manufacture, and relates to an electric heating tube using hexagonal boron nitride or mixture of hexagonal boron nitride and magnesium oxide as a heat conducting material, in particular to a mixed heat conducting material for a novel electric heating tube. A main body structure comprises a metal tube body, a mixed filler, a resistance wire and accessories comprising a fixed plate, porcelain beads, sealant, a plastic plug, a leading-out bar, a terminal electrodes and screws; a cavity structure of the metal tube body is invariantly bent into a circular, elliptical or spiral geometric structure; parallel structures at two end sections of the metal tube body are fixed on the fixed plate in an interval penetration mode, and fixed screws are arranged at two ends of the fixed plate; and the resistance wire is fixed and electrically connected on the central axis of the cavity of the metal tube body and parallel to two end points on two sides of the tube wall, and the mixed filler is filled between the resistance wire and the side wall of the metal tube body. The electric heating tube has the advantages of high stability and heat conducting efficiency, high-temperature softening prevention in inert gas, long service life, high quality, good insulating property, low dielectric constant and dielectric loss, and safe use.

Description

Technical field: [0001] The invention belongs to the technical field of electric heating tube manufacturing, and relates to an electric heating tube using hexagonal boron nitride or its mixture with magnesium oxide as a heat conducting material, in particular to a new type of mixed heat conducting material for the electric heating tube. Background technique: [0002] The tubular electric heating elements used in the existing electric heating occasions are also called electric heating tubes. Generally, metal tubes are used as the outer shell (stainless steel), and spiral electric heating alloy wires or resistance wires are evenly distributed along the central axis of the tube. The gaps are filled and compacted with good insulation. Magnesia sand with thermal conductivity, both ends of the nozzle are sealed with silica gel. This metal armored electric heating element can heat air or metal molds and various liquid media. It has simple structure, high mechanical strength, high th...

AI Technical Summary

Problems solved by technology

[0005] Compared with the prior art, the present invention has the following advantages: using hexagonal boron nitride or its mixture as the main filling material, it has high stability, high thermal conductivity, good heat resistance, and does not soften at 2800°C in inert gas. Long service life and high quality, good electrical insulation, low dielectric constant and dielectric loss, and strong safety in use under instantaneous overload conditions; the performance of hexagonal boron nitride and magnesium oxide powder is complementary after mixing, so that the quality and performance of the filler remain unchanged Under certain conditions, the price drops; hexagonal boron nitride is a chemically inert material with regular particle shape and good moisture resistance, which can effectively solve the problems of incomplete discharge of water and air in the electric heating tube during manufacturing, and the problem of water oxidation resistance wire and metal inner wall; mixed filler particles Small gaps, easy to discharge excess air and moisture in the electric heating tube; thermal expansion coefficient (25°C)‖11.82*10 -6 , ⊥-0.36*10 -6 Better than using magnesia alone ‖15.46*10 -6 , ⊥-0.65*10 -6 , the expansion coefficient is small, and the pressure on the inner wall after thermal expansion is low, which can solve the problems of seal leakage at both ends of the electric heating tube due to excessive pressure inside the tube, gas ejecting out of the tube, and uneven temperature in each part of the electric heating tube. It is safe.

Images