#estimated from bend strength                    *estimated from tensile strength                            

Note: 1 MPa is approx 145 psi

All our mechanical tests were carried out on UHM's CeTZP billets.  A LECO test machine for our indentation macrohardness tests utilized 30 kg loads; K1c values were calculated from crack lengths derived from these indentation tests using the equation of Anstis el alia (reference 10)

Summary:

• The bend and compression strengths of UHM’s CeTZP are almost similar in magnitude to each other, a feature that has more in common with metals than ceramics. Other monolithic engineering ceramics have compression strengths usually two to ten times their bend strengths.
   

• This could mean that materials engineers might not need to restrict designs using UHM’s CeTZP components to a compressive mode, a design constraint often required when other monolithic engineering ceramics are used.

Table 4 lists the thermal properties of CeTZP engineering ceramic compared to cast iron, aluminum and magnesium alloys (references 7 and 15).

For purposes of material substitution, it is important to note that the thermal expansion coefficient of CeTZP is similar to cast iron. Also, the very low thermal conductivity of CeTZP engineering ceramic makes it a good heat insulator.

An example of combining the exceptional properties of UHM’s CeTZP in high performance applications would be a disk brake caliper piston. When brakes are applied forcefully, a large quantity of heat is generated. A CeTZP brake caliper piston should deform less and should transfer less heat to the hydraulic oil and should thus reduce brake fade and sponginess. Also, the better corrosion resistance of CeTZP will reduce maintenance requirements.

Friction of Metal Sliders on CeTZP

A study on the dynamic friction of metal sliders on CeTZP (reference 6) was carried out between temperatures of 298 and 973K.  Given in Table 5 is a summary of its results.

Table 5 (data obtained from reference 6)

This study indicated that, at room temperature, CeTZP could be used with any of the metals given in Table 5 in un-lubricated applications where steel-steel components are currently utilized, with probably a very low wear rate of CeTZP because of the latter's relative hardness (reference 6).

Note that room temperature steel-steel friction coefficient values are approximately the same (i.e. ~0.1  to  0.15).