Zirconia Ceramic Rods are cylindrical parts used to locate, guide, space or insulate. The geometry is simple; the tolerance requirements rarely are.
Zirconia rods are chosen where a rod takes side load or impact, since Y-TZP absorbs the contact stress that would snap alumina in the same geometry. They also suit wear parts running against metal, where the combination of low friction and high toughness holds up under a load that would chip a more brittle rod.
Yttria-stabilised zirconia is the toughest of the engineering oxides, with 8-10 MPa·m½ fracture toughness and flexural strength to 1200 MPa. It absorbs the impact and side loads that would crack alumina, and it carries the lowest thermal conductivity of the structural ceramics here.
Two limits apply. Continuous service above roughly 800-1000°C destabilises the metastable tetragonal phase, and moisture between 200 and 300°C can trigger low-temperature degradation, so stabiliser grade is matched to the duty.
Specifications
| Diameter range | 1-60 mm |
| Length | up to 500 mm |
| Diameter tolerance | ±0.01 mm standard, ±0.002 mm ground |
| Straightness | 0.02 mm per 100 mm |
| Surface finish | Ra 0.4 µm as ground, Ra 0.05 µm polished |
| End configuration | chamfered, radiused, flat, stepped or threaded |
Zirconia Properties
| Composition | Yttria-stabilised zirconia (Y-TZP) |
| Density | 6.00-6.05 g/cm³ |
| Vickers hardness | 1200-1350 HV |
| Flexural strength | 900-1200 MPa |
| Fracture toughness | 8-10 MPa·m½ |
| Max. service temperature | 800-1000°C |
| Thermal conductivity | 2-3 W/m·K |
| Thermal expansion (20-1000°C) | 10.0 ×10⁻⁶/K |
Machining and Tolerances
Rods are centreless ground from extruded or isostatically pressed stock, then lapped or polished to finish. Straightness is the hardest requirement on long parts, and we check it along the full length rather than at the two ends, because a bowed rod can measure in tolerance at both ends and still bind in service.
Where It Is Used
- Guide and locating pins in fixtures and assembly equipment
- Insulating shafts in furnaces, heaters and analytical instruments
- Plunger stems and valve push rods in metering pumps
- Wear rollers and thread guides in textile and wire machinery
- Spacers and standoffs in high-voltage and vacuum assemblies
Frequently Asked Questions
How straight can a ceramic rod be made?
Straightness is held to 0.02 mm per 100 mm as a working standard. We measure along the full length rather than at the two ends, because that is the condition that decides whether the rod will bind in a bore.
Can you put a shoulder, a thread or a cross hole on a ceramic rod?
Yes. Steps, shoulders and cross holes are ground into the blank. Sharp internal corners are avoided in the design because they concentrate stress in a brittle material, so a radius is always used instead.
