Zirconia Toughened Alumina Ceramic (ZTA): When Strength Meets Toughness

Alumina ceramics are widely used due to their excellent mechanical properties, electrical performance, and chemical stability. However, they are highly brittle and have relatively low fracture toughness, typically in the range of 2.5–4.5 MPa·m¹ᐟ², which severely limits their application in more demanding fields. As a result, enhancing the fracture toughness of alumina ceramics has become a key focus in the sector. Zirconia Toughened Alumina (ZTA) combines the high strength and hardness of alumina with the superior toughness of zirconia, making it a highly valued advanced ceramic material.

 What is ZTA Ceramic?

ZTA, short for Zirconia Toughened Alumina, is a kind of advanced multiphase ceramic material. It is based on alumina (Al₂O₃) matrix and incorporates a certain proportion of zirconia (ZrO₂) as the toughening phase. The zirconia is usually present in a partially stabilized tetragonal phase, forming a uniform composite structure with the alumina matrix. 

Pros and Cons of Zirconia Toughened Alumina Ceramics

In Zirconia Toughened Alumina (ZTA), the ratio of alumina (Al₂O₃) to zirconia (ZrO₂) is not fixed and can be adjusted according to performance requirements. However, a typical range is: Al₂O₃ 70–95% and ZrO₂ 5–30%. Mingrui Ceramic’s ZTA ceramics feature 80% alumina and 20% zirconia, ensuring both high strength and excellent toughness. The performance characteristics of Mingrui Ceramic ZTA ceramic are as follows:

Ceramic density: ≥ 4.1 g/cm³

Rockwell hardness: ≥ 90 HRA

Vickers hardness: ≥ 1300 HV

Fracture toughness: 6.0 MPa·m^0.5

Flexural strength: 480 MPa

Compressive strength: 3600 MPa

 

ZTA20 Performance Index of Ceramic Granulation Powder

Parameters	Value
Batch No.	1906298
Quantity	0.05T
Al₂O₃ %	80
ZrO₂ %	20
Apparent density (g/cm³)	1.16
Moisture %	0.45
Blank body density (g/cm³)	2.37
Sintering temperature (°C)	1600
Hold time (h)	2.5
Average shrinkage %	18.29
Finished ceramic density (g/cm³)	4.20
Particle size distribution (Mesh)	60–250
Blank body strength	135
Color	white
Inspector	02
Inspection result	Qualified

*Note: Data tested under the experimental conditions of our company. The diameter of the blank is φ22, weight is 10g, pressure is 80MPa.

 

Toughening Mechanisms of ZTA Ceramics

 

Zirconia (ZrO₂) is a metal oxide ceramic that possesses high hardness, a high melting point, and excellent chemical stability. At room temperature, pure zirconia exists in the monoclinic phase (m-ZrO₂). As the temperature rises to 1170°C and 2376°C, it transforms into the tetragonal phase (t-ZrO₂) and the cubic phase (c-ZrO₂), respectively. Under stress induction, tetragonal zirconia transforms back into the monoclinic phase, accompanied by a volume expansion of approximately 5%.

 

When zirconia is added to an alumina matrix, it enhances toughness by Inhibiting crack propagation along grain boundaries, suppressing abnormal grain growth during sintering and providing phase transformation toughening.The toughening mechanisms of ZTA ceramics generally include stress-induced phase transformation, microcrack toughening, dispersion toughening, and surface compressive toughening. The improved toughness is the combined result of these mechanisms.

 

Applications of Zirconia Toughened Alumina Ceramics

 

1. Biomedical Applications

（1）Dentistry

Dental ceramics have excellent biocompatibility, mechanical strength, and aesthetic performance. Compared with single-phase ceramics, multiphase ceramics offer superior toughness, hardness, corrosion resistance, and high-temperature stability. ZTA ceramics are among the most extensively studied materials. Clinical studies show that ZTA combines the advantages of alumina with the high strength and fracture toughness of zirconia, making it ideal for dental implants and orthodontic brackets.

 

Zirconia Toughened Alumina (ZTA) Dental Implants – Material Source: CeramTec

 

 

(2) Ceramic Artificial Joints

Joint replacement surgery is an essential therapeutic method for advanced arthritis, loss of joint function and other joint diseases. Due to their high hardness and excellent biocompatibility, ZTA ceramics have been applied in artificial hip joints. Their strong corrosion resistance and chemical stability significantly reduce complications such as osteolysis, implant loosening, and infection.

 

2. Industrial and Mechanical Engineering

(1) Pumps and Valves

Zirconia toughened alumina ceramic can be used for ZTA ceramic plungers, seals, and linings in the chemical and petroleum industries to resist corrosive fluids and abrasive slurries.

 

(2) Cutting Tools

ZTA inserts are ideal for high-speed machining of hardened steels and cast iron, with zirconia toughening reducing the risk of chipping under thermal shock.

 

3. Semiconductor

(1)  Semiconductor Packaging Substrates

Compared with conventional alumina substrates, ZTA ceramic substrates for semicondudctor exhibit higher flexural strength and are widely used in high-reliability and long-lifetime applications. On account of excellent thermal conductivity, electrical insulation, thermal shock resistance, and mechanical strengsemiconductorth, ZTA substrate sheets are extensively used in EV IGBT modules, LEDs, and other semiconductor devices.

 

Zirconia Toughened alumina ceramic plates produced by Mingrui Ceramics combine high hardness, wear resistance, and excellent toughness, along with outstanding electrical insulation and thermal stability. They are suitable for semiconductor packaging, electronic and electrical components, and high-temperature precision structural parts, providing reliable high-performance solutions.

 

ZTA Plate Sheet – Source: Mingrui Ceramic

 

(2) Ceramic Capillary

A ceramic capillary is an axisymmetrical ceramic tool with a vertical central hole, primarily used as a bonding tool during the wire bonding process in semiconductor packaging. ZTA ceramic capillaries offer excellent mechanical properties, reducing tip wear and replacement frequency during bonding.

 

(3) Cutting Tools

High-speed cutting requires tool materials to maintain mechanical strength, chemical stability, and anti-adhesion performance at elevated temperatures. Zirconia Toughened Alumina is an ideal cutting tool material, combining the flexural strength of zirconia with the rigidity of alumina. ZTA ceramic cutting tools exhibit low flank wear and are suitable for applications requiring wear resistance, corrosion resistance, high-temperature stability, and excellent mechanical strength. They remain stable under high cutting temperatures and are capable of machining cast iron and alloy materials.

 

(4)Vacuum Components

Used in wafer processing equipment where chemical inertness is necessary.

 

In addition to the fields mentioned above, zirconia toughened alumina ceramic parts are also used in a variety of other applications due to their excellent mechanical properties, chemical stability, and biocompatibility, such as aerospace and defense, as well as optics and precision instruments. 

 

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