Guides / Materials

Not All Zirconia Is the Same: 3Y-TZP, 5Y, ZTA and ATZ

April 20, 2026

Ordering “zirconia” is like ordering “steel”. The stabiliser content decides whether you get the toughest common technical ceramic or a translucent material designed to look like a tooth.

Pure zirconia is unusable as a structural part because it changes crystal phase on cooling and tears itself apart. Adding yttria holds a useful phase in place at room temperature, and how much yttria you add is the whole story.

The grades you will meet

Grade	Stabiliser	Character	Typical use
3Y-TZP	3 mol% yttria	Toughest, opaque, fine grain	Plungers, dies, blades, nozzles, industrial parts
4Y	4 mol% yttria	Slightly less tough, more translucent	Dental, some optical work
5Y	5 mol% yttria	Noticeably less tough, translucent	Dental crowns and bridges
ZTA	Alumina matrix with 10 to 20% zirconia	Stiffer, harder, cheaper than TZP	Wear parts, structural parts that crack in alumina
ATZ	Zirconia matrix with alumina added	Slightly harder and more ageing resistant than 3Y	Medical, demanding wear
Mg-PSZ	Magnesia stabilised	Coarse grain, tough, high temperature tolerance	Metal forming tools, hot handling

For an industrial machined part, 3Y-TZP is the default and everything else needs a reason.

Why the yttria number matters so much

3Y-TZP is almost entirely tetragonal grains held in a metastable state. When a crack front arrives, grains ahead of it transform to monoclinic and expand slightly, which clamps the crack. That transformation toughening is why 3Y-TZP reaches fracture toughness around 9 to 12 MPa m^0.5 while alumina sits near 4.

Add more yttria and more of the structure becomes cubic. Cubic grains do not transform, so they do not toughen. They do scatter less light, which is why dental materials went that way. A 5Y part can be half as tough as a 3Y part while looking identical on a purchase order.

If someone offers you dental blanks for an industrial job because they are in stock, that is the trade you are making.

Grain size and the ageing question

3Y-TZP is sensitive to hot humid service. Water vapour at roughly 150 to 400 degrees C can trigger the same tetragonal to monoclinic transformation from the surface inward, which roughens and microcracks the skin of the part. Finer grain size, a little extra yttria, alumina additions or ZTA and ATZ all slow it down.

This is not a reason to avoid zirconia. It is a reason to tell the shop that the part will be steam sterilised, run in hot water or sit in humid heat, so the right grade gets quoted. The detail is in zirconia ageing.

Black, white and coloured zirconia

Zirconia is naturally off white. Pigmented grades exist, and black zirconia is common where the part is inside an optical instrument or a camera path and stray reflection matters. Pigments change the sintering behaviour slightly, so the available sizes are narrower and the price is higher. Ask before you specify a colour on a functional part.

What to put on the drawing

• The grade family and stabiliser, for example 3Y-TZP, not just zirconia
• Whether the part sees hot water, steam or humid heat
• Whether a colour is functional or cosmetic
• Density as a minimum percentage of theoretical, if the part is loaded or sealing
• Grain size, if the part has a thin section or a fine ground edge

Everything else, including tolerance and finish, follows the same rules as any ground ceramic. See realistic tolerances and surface finishes and, for the alumina comparison, alumina or zirconia.

For how zirconia fits against the other families and the specification line, see ceramic material selection.

See also: the 3Y-TZP zirconia reference page.

Send your drawing and we match it with up to 3 shops that grind the grade you need. Reply within 24 business hours.

Frequently asked questions

Keep reading

• Yttria Ceramic in Plasma Etch Chambers: Why It Replaces Alumina and Quartz
• Steatite or Forsterite: Choosing a Magnesium Silicate Insulator