Humans and been making knives and cutting tools since the Stone Age. For thousands of years humans have been making knives out of steel. The 20th century has brought about technology allowing us to synthesize a variety of new materials into knives harder than steel. These non-melting materials which are made by firing inorganic, non-metallic substances at very high temperatures. Japan was one of the first countries to really pioneer making knives from zirconium oxide due to its exceptional hardness.
While it may be true that zirconium oxide is much harder than steel knives they are not however second in hardness only to diamond. But they are very close in hardness which makes them ideal for retaining their sharp edge.
The difference between zirconium oxide and zirconium carbide is that zirconium carbide makes a black blade and the carbide mixed in is a bit harder than the zirconium oxide, thus giving it a competitive edge. In short, the black zirconium carbide blades are stronger than the white zirconium oxide blades.
So what makes a ceramic knife better than steel you ask? Well it’s because of its extreme hardness, the edge of the ceramic blade doesn’t wear way as fast as a steel blade. Thus lasting 10 times longer. They are stain proof, rustproof, and much lighter than steel.
But don’t be full because hardness is not the same as tensile strength or flexibility. Ceramic knives are very inflexible and inclined to break if used in prying or twisting motions. For instance, you would not use a ceramic knife for crushing garlic because the knives can chip.
Have your doubts? So did I. But while doing research for this column, I fell madly in love with a Wilson six-inch ceramic Santoku chef's knife. It was so astoundingly sharp that I could cut a sheet of paper in two without even having to draw the blade across the paper's edge.