20–25mm Pressureless Sintered SiC Thermocouple Protection Tubes

Name: 20–25mm Pressureless Sintered SiC Thermocouple Protection Tubes
Brand: Shaanxi KeGu New Material Technology Co., Ltd
SKU: Customizable
Availability: InStock

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NGK values our long-standing partnership with Shaanxi Kegu. Their SSiC ceramics excel in quality and innovation, driving our mutual success. Here’s to continued collaboration!

—— NGK Thermal Technology Co.,Ltd

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20–25mm Pressureless Sintered SiC Thermocouple Protection Tubes

Large Image : 20–25mm Pressureless Sintered SiC Thermocouple Protection Tubes

Product Details:

Place of Origin:	China
Brand Name:	KEGU
Model Number:	Customizable

Payment & Shipping Terms:

Minimum Order Quantity:	Negotiable
Price:	Negotiable
Packaging Details:	Strong wooden box for Global shipping
Delivery Time:	Negotiable
Payment Terms:	L/C,D/A,D/P,T/T,Western Union,MoneyGram

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20–25mm Pressureless Sintered SiC Thermocouple Protection Tubes

Description

Highlight:

Sintered SiC Thermocouple Protection Tubes

25mm Sintered SiC Thermocouple Protection Tubes

20–25mm Pressureless Sintered SiC Thermocouple Protection Tubes

Product Overview

Designed for harsh high-temperature and corrosive environments including coal gasifiers, hot blast stoves, non-ferrous metal smelting, and sulfuric acid concentration plants. The 25mm OD / 20mm ID configuration with 2.5mm wall thickness balances mechanical strength and thermal response time, establishing it as the industrial standard size.

Specification	OD (mm)	ID (mm)	Wall Thickness (mm)	Typical Length (mm)
Mainstream type	25	20	2.5	900–950

Key Performance Parameters

Parameter	Value	Unit
SiC content	≥98	wt%
Density	≥3.10	g/cm³
Apparent porosity	0	vol%
Flexural strength	400–550	MPa
Compressive strength	>2500	MPa
Thermal conductivity (25°C)	120–270	W/(m·K)
Coefficient of thermal expansion (25–500°C)	3.8	*10⁻⁶/K
Max. service temperature (oxidizing)	1600–1750	°C
Max. service temperature (protective atmosphere)	1900–2000	°C

Manufacturing Process: Cold Isostatic Pressing + Pressureless Sintering

Cold Isostatic Pressing (wet-bag method)

Pressure: 150–300 MPa, isostatic (uniform in all directions)
Green relative density: 55%–62%
Advantages: Uniform wall thickness (deviation ≤0.2mm), no density gradient, smooth inner bore, length-to-diameter ratio >20:1, no post-sintering distortion

Pressureless Sintering (solid-state sintering, B+C additives)

Temperature: 2020–2220°C under argon or vacuum
Achieved density: >98% (near fully dense)
Characteristics: Clean grain boundaries, no free silicon, stable high-temperature performance

Comparison: SSiC vs. Reaction-Bonded SiC (RBSiC)

Property	SSiC (pressureless sintered)	RBSiC (reaction-bonded)
SiC content	≥98%	~82%
Free silicon	None	~17%
Max. service temperature	1650–1750°C	<1400°C (free silicon melts)
Flexural strength	400–550 MPa	250–350 MPa
Resistance to strong acids/bases	Excellent	Poor
Density (apparent porosity)	0% porosity	Open porosity present

Core Technical Advantages

Ultra-high temperature resistance: Long-term use at 1600–1750°C in oxidizing atmospheres
High thermal conductivity: 270 W/(m·K), 4–5 times that of alumina
Outstanding thermal shock resistance: Low CTE (3.8*10⁻⁶/K), withstands 300°C/min thermal shock
Strong corrosion resistance: Insoluble in hydrochloric acid, sulfuric acid, molten aluminum/zinc
High mechanical strength: Flexural strength ≥400 MPa, compressive strength ≥2500 MPa
Fully dense and gas-tight: Zero porosity prevents corrosive gas penetration
CIP-enabled dimensional precision: Uniform wall thickness, straightness ≤0.5 mm/m, no deformation of thin-walled tubes

Typical Applications

Industry	Specific Application	Temperature Range
Chemical	Coal gasifiers, sulfuric acid concentration towers	1200–1650°C
Metallurgical	Molten aluminum/copper/zinc bath temperature measurement	700–1700°C
Iron & Steel	Hot blast stove domes, continuous casting	1000–1500°C
Kilns	Cement rotary kilns, glass melting furnaces	900–1600°C

Supplementary Information

Installation & Sealing Recommendations

Use a loose flange or flexible graphite gasket seal; avoid rigid connections that may induce thermal stress cracking
Leave a 3–5 mm expansion gap between the protection tube and furnace wall; the tube bottom must not contact internal furnace components

Comparison with Other Common Thermocouple Protection Tube Materials

Material	Max. Service Temp (°C)	Acid/Alkali Resistance	Thermal Shock Resistance	Cost	Suitable Application
SSiC (this product)	1750	Excellent	Excellent	High	>1400°C, strong corrosion
Alumina (99%)	1600	Good	Fair	Medium	Clean atmospheres, mild acids/alkalis
Metal alloy (e.g., Inconel)	1100	Poor	Good	Medium–High	Low temperature, reducing atmospheres
Fused silica	1100	Not alkali-resistant	Excellent	Low	Short-term, low-temperature measurements

Service Life & Reliability

Under continuous use at 1600°C in oxidizing atmospheres, design life is 2–5 years, 5–10 times longer than high-temperature alloy tubes
CIP-formed tubes, free from internal defects, exhibit a first-year failure probability <0.1%
Main failure modes: thermal shock-induced through-cracks (70%), mechanical impact damage (20%), alkali attack (10%)

Customization & Certifications

Available lengths: 200–1500 mm; ODs from 15–60 mm; ID tolerance after grinding: ±0.05 mm
Compatible flange materials: 304, 316L, Hastelloy; sealing faces: flat, raised, tongue-and-groove
Compliant with ASTM C1793 (Standard for Pressureless Sintered Silicon Carbide) and GB/T 25942-2010

Summary

The 25*20mm pressureless sintered SiC (SSiC) thermocouple protection tube, manufactured by cold isostatic pressing (CIP) followed by pressureless sintering, delivers exceptional high-temperature capability, strong corrosion resistance, high thermal conductivity, and uniform dimensional precision. It is the preferred protective sheath for demanding applications above 1400°C. The above installation, comparison, lifetime, and customization data provide practical guidance for selection and use.

For further information or to discuss your specific requirements, please contact us directly.

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Contact Person: Miss. Scarlett.S

Tel: 8616602956098