Alumina (Al2O3) is a versatile ceramic and a ‘workhorse’ ceramic that finds place in a wide range of applications— mechanical, thermal, electrical, electronic and even optic. Indian industries are well-versed in alumina products for applications like refractory bricks, insulator tubes, crucibles etc. But, alumina components for electronic and similar high-tech applications are still imported. The drawback of pure alumina for electronic applications is the large temperature-coefficient of relative permittivity. Currently imported alumina ceramics suffer from high drift of dielectric constant with temperature and need firing temperature above 1600°C. But, the compensated alumina (ComAl), developed by VSSC, has near-zero temperature coefficient and can be sintered at =1475°C.

The ceramic has alumina as major content and a couple of additives and dopants. The powder of ComAl can be suitably processed further for making bulk ceramics, thin tapes etc. as per requirement. Bulk green bodies can be fired at =1475°C for less than 2h to get sintered ceramic. Sintered products can be polished, sliced or cut or machined for various applications. Typical properties of bulk ceramics are shown below:


Firing temperature(°C)

1450 – 1475

Bulk density (g/cc)

3.9 ± 0.1

Resistivity (


Coeff. of Thermal Expansion (10-6/K)

7 – 7.2

Thermal conductivity (W/m.K)

24 – 30

Dielectric constant (er) @ 5GHz

11 – 12

Dielectric strength (kV/mm)

9 – 10

Loss factor (tand, 10-5) @ 6 GHz

< 7

Qu of resonator @ 12GHz

> 10,000

Temperature coefficient of er (ppm/K)

(–)7 – 20

Temp. coeff. of frequency (tf, ppm/K)

0 ± 3


ComAl ceramics can replace conventional alumina ceramics in various electrical, electronic and RF applications like substrates for HMC and MIC, dielectric resonators for filters/oscillators above 10GHz.

Interested entrepreneurs are requested to contact the address given below with all relevant particulars regarding their line of current activity, infrastructure available, market assessment of the product, financial arrangements made, turn over and sales of their products for the past years and a copy of their latest annual report.


ISRO is willing to offer the knowhow of this technology to suitable entrepreneurs / industries in India. Capable manufacturing industries interested in acquiring this knowhow may write with details of their present activities, requirements and plans for implementation, infrastructure and technical expertise available with them, their own market assessment, if any, and plans for diversification to the address given below:


Technology Transfer & Industrial Coordination Division (TT&IC)

Vikram Sarabhai Space Centre, ISRO PO

Thiruvananthapuram-695 022

E mail: This email address is being protected from spambots. You need JavaScript enabled to view it.

Ph: 0471-2564081

Fax: 0471-2564134

Ph: 0471-2564081/2565133/2565695

Fax: 0471-2564134