Silicon Carbide Thermocouple Protection Tube

Introduction Silicon Carbide Thermocouple Protection Tube

The general wall thickness of silicon carbide heat protector for thermocouples is 5-6mm (except for special requirements). An external protection tube that is used directly for thermocouples can extend the lifespan of the thermocouple and increase the recovery of even filaments. In the case of allowing the user to leave the hole in the furnace, try to use the larger diameter holes for both outer and inner (does not affect the accuracy of temperature measurement) to protect the selection of the inner hole of the tube: the length of the thermocouple × 6 ‰ + the outer diameter of the thermocouple porcelain tube. The galvanic protection tube of other materials is easily deformed and the silicon carbide thermocouple protection tube is deformed little.

Characteristics Silicon Carbide Thermocouple Protection Tube

The choice of protection tube length: depth of furnace + furnace wall thickness + part of the furnace to stay (about 20–20mm).
When the thermocouple used for lifting is added with protective tube, the part of the silicon carbide protective tube left outside the furnace is recommended to be fixed with a clamp.
When the silicon carbide heat protection tube is installed, the galvanic coupling should be slowly inserted into the furnace at the same time, and it can be used without preheating.
Directly use silicon carbide protection tube instead of other materials protection pipe fittings recommended the following method:

The platinum wire is generally drilled into an 8mm diameter 2 hole ceramic column. The end of the ceramic column is dropped with a diamond file (or a hacksaw blade) in a small groove of 1.5–2mm, and the platinum wire node is placed in the groove.
Made the Alumina powder or magnesium oxide powder into a paste with a 15% solution of aluminum dihydrogen phosphate (molar ratio of phosphoric acid and aluminum hydroxide is 3:1), and then use it to seal the small groove at the end of the porcelain tube. Platinum wire combined sealed in the tank.
Heat the end of the sealed porcelain tube in an oven to cure it at a temperature of about 150°C.
Re-install the even-silvered porcelain column into the selected silicon carbide recrystallizing sleeve and assemble it into a thermocouple, which can be used reliably.
It is also optional to install a layer of corundum tube inside the larger silicon carbide protection tube with inner hole to protect it.
Generally 1200mm length of silicon carbide protection tube can be assembled into a thermocouple of more than 2000mm, its method is to repeat the above procedure, but also need to select a seamless steel tube (the inner hole is larger than the diameter of silicon carbide protection tube ) 900mm length, with it and silicon carbide protection tube socket lengthened. The sockets are cemented with aluminum dihydrogen phosphate dial cement, fixed and cured by bonding, and can be assembled.

Technical Data Sheet of Silicon Carbide Thermocouple Protection Tube

Item	Unit	Data
Max Working temperature	℃	1380
Density	g/cm³	≥3.02
Porosity	%	<0.1%
Bending Strength	Mpa	250(20℃)
Bending Strength	Mpa	280(1200℃)
Modulus of elasticity	Gpa	330(20℃)
Modulus of elasticity	Gpa	300(1200℃)
Thermal conductivity	W/m.k	45(1200℃)
Coefficient of thermal expansion	K-1×10-6	4.5
Rigidity		13
Acid alkaline-proof		Excellent

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