Materials Synthesis and Development

Group

ZTC: partially stabilized ZrO2 ceramics with high TiC-content

Topic

Advanced zirconia composites with high microscopic wear resistance and hydrothermal stability

Pressureless sintered or hot-isostatically pressed zirconia ceramics with high carbide content are characterized by a microstructure with all grains in the submicrometer range and with grain boundaries that are free of any amorphous films. Unique compositions and technological approaches are developed to meet special requirements in technical applications and are used to produce individual prototypes and small series.

 

Advantages

 

The material unites the advantages of well-known yttria stabilized ZrO2 - ceramics as a high strength and an extremely fine-grained microstructure with:

  • a significantly improved hardness and wear resistance (e.g. wear rate of ZrO2/TiC against Al2O3 in dry air is 1/10 of the wear rate of Y-TZP with the same grain size)
  • doubled thermal conductivity
  • enhanced mechanical and hydrothermal aging resistance because of reduced subcritical crack-growth (e.g. constant strength and hardness after 140 hours at 220 °C/H2O

The good electroerosive processability of this material provides additional advantages for the production of parts made of this material. Another important merit of the developed technology is the possibility to achieve improved properties without expensive hot pressing.

 

Application

 

  • Ceramic knives for the medical applications (microtomes), for machines in the paper and textile industry, and for equipments in the processing of viscous masses
  • Sliding head substrates in data storage systems
  • High precision wear-resistant parts (e.g. ball bearings, chucks for the automatic change of tools)
  • Substitution of ZrO2 to enable advantageous electroerosive processing of parts
     
Properties Typical data
  sintered sintered + HIP
Density g/cm3 5,1 - 5,6 (depends on Al2O3)
Grain size µm 0.6
Sourface roughness Ra (after polishing) nm 3 - 5
Young´s modulus GPa 270 330
Bending strength MPa 900 - 1000 1000 - 1200
Fracture toughness Kic MPa m1/2 5 - 6
Vickers hardness HV 10   1500 1600 - 1700
Electrical resistance m Ω cm 3
Heat conductivity W/mK  

Properties given for ZrO2 + 35vol-% TiC (+ Al2O3)