General Purpose Ceramic Knife

A general purpose ceramic knife with plastic sheath.

WARNING

Do not try to use any coarse diamond files or round/triangular rods. These will chip the edge as will most commonly used sharpening tools. A powered diamond abrasive with very fine grit 1,000 or finer, will produce a clean edge but may require further polishing to remove scratches and micro chips for the absolute best edge! I have found that a small 600 grit diamond coated steel plate does work very well to re-define an edge or remove chips etc. Actually a good working edge but further polishing with 1,000 and 1,500 grit SC paper will further improve this.

Ceramic blades - SHARPENING ADVICE

YES it is much more difficult to sharpen ceramic blades due both to the extreme hardness AND the tendency of creating micro-chips on the edge. BUT it is not impossible to both repair small damage or chipping and also to polish and refine the edge to a very high level of sharpness.

The ideal tool of course is a powered diamond wheel with a minimum of 1,000 grit diamond. Even finer grits can be used to truly polish the edge. However, no one I know, except myself, is willing to purchase this kind of equipment. 

Polishing the edge to get a higher degree of sharpness if it does become uniformly 'dull' can be accomplished with very, very fine silicone carbide wet/dry sandpaper. This is not a fast process but does work and I have been including a small strip of 1500 grit paper with knives sold.

Instructions: Put paper on top of mouse pad or piece of cardboard to provide some compression and better control of knife angle. Now draw the blade away from the edge, (do not cut into the paper), with only a slight elevation of the back of the blade. 20 strokes on each side and then test the edge. You can use from 800 to 2,000 grit paper. Start coarse IF there is more than just polishing required.

Grinding out chips or damage to the edge or re-shaping the edge.

Geometry is really only possible using a diamond hone. Powered would be really fast and then you can use a very fine grit. Using a small diamond hone (such as such as the one we supply) with a 600 grit does permit fairly quick removal of ceramic from the edge. I have found that 600 grit offers the best compromise between rapid removal of material AND an acceptable working edge. Water is used as a lubricant and no more pressure than you would use with a steel blade on a hone. These diamond hones can be used on your steel knives but keep in mind that you will find the steel is VERY RAPIDLY removed from the edge! Actually a very useful tool to carry in your wallet!

TECHNICAL DETAILS

Ceramic knives are a modern innovation. The hardness, strength and corrosion resistance of Zirconia (ZrO2) Ceramic, provides significant advantages compared to traditional stainless steel knives: the ultra-sharp ceramic blade will hold its edge much longer than regular steel, go literally years without re-sharpening when you use these stain and rust proof knives! Impervious to food acids that eventually discolour steel products. Ceramic knives do not leave behind any metallic taste or smell, helping to maintain each food's taste. Your Ceramic Knife is an environmental, friendly, chemically stable product, which is rust-free and non-corrosive. The non-stick surface is easier to clean than steel and will not tarnish or absorb food odors, they are easy to care for by rinsing in warm water, and they do not need to be fully dried when stored.

COMPOSITION

Technical Info.

Zirconia Ceramic (ZrO2)
Material Composition

• ZrO2>94.4, Y2O3 5.25, SiO2<0.015, Fe2O3<0.01, Na2O<0.01, Al2O3<0.25, Cl-<0.01

Material Properties

• Specific density: 5.95g/cm
• Hardness (HV):  >1100-1250, Bending strength 1150Mpa
• Fracture toughness:  7-10
• Grain size:  <0.5um
• Elastic modulus:  205Gpa
• Thermal conductivity:  3w/m ? k,
• Thermal expansion coefficient:  20-400

NB: The Black coloured blades are the same basic material only subjected to a further 24 hours of high temperature & pressure to produce the permanent black color and a slight degree of additional hardness. (Upper end of scales) 

FAQs

Are Ceramic blades Fragile?

Not fragile as much as very different from steel - note that even steel when taken to extreme hardness levels will snap or break if you attempt to bend it. You see this more often with very hard drill bits that tend to break at tips when any side force is exerted. You can, most times drop a ceramic knife and as long as it does not fall right on the pointy end no damage is likely.

You cannot use a ceramic blade as a pry bar ! Cutting into hard wood really does not cause a problem EXCEPT when you exert force on an angle (trying to bend that edge right - ! This might snap the blade but more likely will cause some small chips on the edge. Same thing with cutting through chicken bones - cut straight & you will likely succeed but that is not easy to do with these small blades.

Salt Water?

The ceramic blades really do not react with much in the way of chemicals, not reactive to vinegar or other food acids! BUT with the 400 series stainless steel handles you really do have to flush off salt water as even stainless steel is not totally corrosion resistant. And of course, salt or sand particles will tend to jam up the pivot. Close the knife & throw in dishwasher if it gets truly dirty.

Care and Feeding

The ceramic blades are very, very abrasion resistant which means they will retain their sharpness at least 10 times longer than steel blades and depending upon what you are cutting up to 40 times as long. BUT eventually you will have to touch up the edge. Read my Sharpening page for some suggestions. The stainless steel bodies on these knives use a number of small 'stainless steel' screws and nuts. Bouncing around in your pocket everyday can cause these to work a bit loose, especially the pivot pin. You can even hand tighten this using fingernails if it works lose. The Lanyard ring has also reported to come loose from time to time so check it every month or so.