Metallized Ceramic Alumina Insulator for High Voltage Current Electrode

Product Description

Metallized Ceramic Alumina Insulator for High-Voltage Current Electrode
 

Product Description

 

Introduction to Structural Ceramics

Structural materials are mainly various materials using their mechanical properties such as strength, hardness and toughness.

Metals have been widely used as structural materials, but metal materials have disadvantages such as easily corroded and not resistant to oxidation at high temperatures.

The emergence of ceramic structural materials makes up for the shortage of metal materials. Ceramic structural parts have the advantages of being able to withstand high temperatures, no fear of oxidation, acid and alkali corrosion resistance, high hardness, wear resistance, and low density. Their application fields continue to expand, and the market growth rate is also considerable.

What Raw Materials are Used in Ceramic Structural Parts?

Considering cost-effectiveness, we generally choose alumina, aluminum nitride, zirconia, silicon nitride, etc. Among them, Alumina ceramics are the most widely used.

 

Product Parameters

The relevant properties of alumina ceramics are shown in the table below.

 

Category	Property	Unit	99.8% Al2O3	99.5% Al2O3	99% Al2O3	95% Al2O3	94.4% Al2O3
Mechanical	Density	g/cm^3	≥3.95	≥3.90	≥3.85	≥3.65	≥3.60
	Water absorption	%	0	0	0	0	0
	Vickers hardness	HV	1700	1700	1700	1500	1500
	Flexural strength	Mpa	≥ 390	≥ 379	≥ 338	≥ 320	≥ 312
	Compressive strength	Mpa	≥ 2650	≥ 2240	≥ 2240	≥ 2000	≥ 2000
	Fracture toughness	Mpam^1/2	4-5	4-5	4-5	3-4	3-4
Thermal	Max. Service temperature (non-loading)	ºC	1750	1675	1600	1500	1500
	CTE (Coefficient of thermal expansion) 20-800ºC	1×10^-6/ºC	6.5-8.2	6.5-8.0	6.2-8.0	5.0-8.0	5.0-8.0
	Thermal shock	T (ºC)	≥ 200	≥ 200	≥ 200	≥ 220	≥ 220
	Thermal conductivity 25ºC	W/(m·k)	31	30	29	24	22.4
	Specific heat	1×10^3J/(kg·k)	0.78	0.78	0.78	0.78	0.78
Electrical	Volume resistivity 25ºC	ohm·cm	> 1×10^14	> 1×10^14	> 1×10^14	> 1×10^14	> 1×10^14
	300ºC		1×10^12	1×10^12	8×10^11	10^12-10^13	10^12-10^13
	500ºC		2×10^12	5×10^10	2×10^9	1×10^9	1×10^9
	Dielectric strength	KV/mm	20	19	18	18	18
	Dielectric constant (1Mhz)	(E)	9.8	9.7	9.5	9.5	9.5

Production Process

Our product production is mainly divided into 3 steps: forming, finishing, and metallization. The production flow chart is shown below.

Forming	Finishing	Metallization
We will choose the most suitable forming method on the basis of saving costs and ensuring quality.	In order to achieve the precision of the product, most ceramic structural parts need further finishing treatment after the sintering process.	Metallization of ceramics refers to the creation of thin metal layers (films) on the surface of ceramics. After the surface of the ceramic material is metallized, it has both the characteristics of ceramics and the properties of metal.

What are the Methods of Metallization of Ceramic Structural Parts?

Common methods are shown in the table below. Each method has its own advantages and disadvantages, and it needs to be considered comprehensively in practical applications to decide which method to use.
 

Common Metallization Process	Process Description	Advantages	Disadvantages
Electroless Nickel Plating Method	Ceramic Body + Electroless Ni Plating	1. Uniform coating and small pinholes. 2. Low cost, suitable for mass production.	Low bonding strength
Silver Firing Method	Ceramic Body + Ag Coating	1. Silver has strong electrical conductivity and good oxidation resistance. 2. The fired silver layer is firmly bonded, and the thermal stability is good. 3. The process is simple and easy to implement.	1. Thin, discontinuous and uneven film layer. 2. Higher cost.
Mo-Mn Method	Ceramic Body + Mo-Mn Metallization + Electroplating or electroless Ni plating	1. The most important one in the metal powder sintering methods. 2.  Mature and stable process, and high bonding strength. 3. To prevent oxidation and improve wettability, after the metallized Mo layer is sintered, a Ni layer can be plated on it.	The film layer is discontinuous, uneven, and rough.
W-Au Method	Ceramic Body + W Metallization + Au Plating	1. Tungsten metallization has the advantages of simple formula, and can meet some special requirements, such as alkali metal vapor resistance. 2. The gold layer is highly conductive and protects against oxidation and increased contact resistance.	The film density is not high.

Below we will focus on the Mo-Mn method.

The Mo-Mn method is to coat metal powders such as Mo powder and Mn powder on the ceramic surface, and then sinter at high temperature in a reducing atmosphere (hydrogen gas), thereby forming a metal layer on the ceramic surface. The following is the brief description diagram.

Product Applications
 

Application of  Al2O3 Structural Parts

1. Semiconductor equipment parts

2. Medical equipment parts

3. Industrial equipment parts

4. Wafer handling parts

5. Insulation shells for electronic devices

Our Advantages

Jinghui has accumulated more than ten years of experience in the field

of metallized ceramic structural parts, and can produce various

specifications of metallized ceramic structural parts according to

customers' drawings, with superior performance. Our customers are

very recognized for our product quality.