High quality polished Corundum tube/bushing, Alumina ceramic bushing

Product Overview

Description

1.Product description

Alumina is the most mature of the engineering ceramics, offering excellent electrical insulation properties together with high hardness and good wear resistance but relatively low strength and fracture toughness. 

During the prodcution, small amounts of silica (SiO2), magnesia (MgO) and zirconia (ZrO2) may be added to alumina ceramics. The applications vary with the purity of Alumina. 99% Alumina Ceramics are mostly used for high temperature crucibles, kiln furniture, special abrasion resistant parts, such as ceramic bearings, ceramic sealings or faucet discs; 95% Alumina Ceramics are usually applied for corrosion-resitant components or wear proof parts; 85% Alumina Ceramis can be metallized with metals like molybdenum, niobium, tantalum to use for electric vacuum devices. 

Properties of Alumina Ceramics 
Alumina has a high melting point, high hardness and high mechanical strength, although mechanical strength is reduced at temperatures above 1000° C. Due to the relatively large coefficient of thermal expansion, thermal shock resistance is reduced. Alumina is an electrically insulating material, with a high electrical resistivity, increasing with purity. Good chemical stability of alumina, leads to a high corrosion resistance. It is insoluble in water and only slightly soluble in strong acid and alkaline solution. 

 

2.Technical Paraeter of Alumina Ceramic

 

 

Technical Parameter Of Alumina Ceramics
Item	Test condition	Unit&Symbol	95%  Alumina Ceramics	99% Alumina Ceramics	99.7% Alumina Ceramics
The Main Chemical Ingredient			Al2O3	Al2O3	Al2O3
Bulk Density		g/cm³	>3.6	3.89	3.96
Maximum Use Temperature		ºC	1450	1600	1650
Water Absorption		%	0	0	0
ROHS Hardness			≥85	≥ 89	≥89
Flexural Strength	20 ºC	Mpa(psi*10³)	358(52)	550	550
Compressive Strength	20 ºC	Mpa(psi*10³)	2068(300)	2600(377)	2600(377)
Fracture Toughness	K(lc)	Mpa m 1/2	4-5	5.6	6
Coefficient Of Thermal Expansion	25-1000 ºC	1*10 -6 /ºC	7.6	7.9	8.2
Coefficient Of Thermal Conductivity	20 ºC	W/mk	16	30.0	30.4
Thermal Shock Resistance	ΔTc	ºC	250	200	200
Dielectricity Constant	1MHz.25 ºC		9	9.7	9.7
Dielectricity Strength		ac-kV/mm(ac V/mil)	8.3(210)	8.7(220)	8.7(220)
Volumn Resistivity	100 ºC	ohm-cm	>10 13	>10 14	>10 14

 

 

 

 

3.Main application:

Feature	Application	Main usage
1.Great mechanical strength	Electric appliance industry                                      Automotive industry	1.Heat treatment furnace and  toughened furnace
2.High softening temperature
3.Good resistance to  thermal impact
4.Small thermal expansion  coefficient	Mechanical industry               Engineer industry	2.Inner liner tube and heating  tube in electric furnace
5.Good chill and abrupt  heat properties
6. Resistance to acid and alkali corrosion