Kyocera Ceramic Kitchen Knives

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me2

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Oct 11, 2003
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Does anyone have one of these that they've compared to a steel knife? I'm having a running discussion about the merits of ceramic vs. steel and need some fairly detailed info. I concede that ceramic is superior for stain resistance, heat resistance, and edge holding, but that steel can get sharper, thinner, and much tougher. Since we are talking kitchen knives, heat resistance isnt really an issue. Does anyone have measurements of geometry to compare to steel knives? Does anyone know if the ceramic is fired to 100% density from the compacted powder blanks? Does anyone know if its possible with the ceramic that's being used?
 
Hi me2.
I had one several years ago, but you’re asking about stuff that’s way over my head.

On the plus side, it was impervious to staining or rust and could hold an edge forever, but had two major problems. First, it’s impossible to sharpen without somesort of powered diamond abrasives. The blade worked best with soft foods (veggies and fish), but no better than a steel knife. Secondly, it’s extremely brittle. Mine snapped, cracked like a windshield shortly after it started to chip (perhaps from a piece of sand). From what I’ve seen the newer ones don’t shatter like glass if accidently dropped on the floor like the older ones did.
 
I had a white Kyocera and it was as sharp as and the edge never needed sharpening which I could not do anyway, but a piece of the tip broke of and I put it in the cupboard where all the old knives go and forgot about it. I have seen a number of different brand names around for a lot less than the Kyocera.
 
I have one. It's great on fruit and veggies. Not so good on cheeses.

Kyocera will regrind broken ones.
 
I have several Kyoceras. The edges don't feel as acute as a really fine steel knife. For example, my Kyoceras don't seem to shave like a Murray Carter kitchen knife will. That said, they have great lubricity and will just slide through veggies, fruits, and boneless meat, chicken or fish.

One of my colleagues had a badly chipped Kyocera and I was able to sharpen it fairly well with a diamond hone.

Sorry I can't answer your technical questions.

DancesWithKnives
 
All I'm after is some basic geometry measurements. Nothing too complicated. At what angle did you resharpen the chipped knife? I can go as low as 12* per side with my favorites, and then the issue is the occasional trip through the dishwasher, not the cutting. What is the spine thickness? How about the thickness behind the edge bevel? When new, would the blades shave hair, whittle hair, push cut paper, slice toilet paper, etc?

I'm not completely sure, but from my ceramics (material science, not pottery) classes years ago, I seem to remember 100% density being practically impossible for ceramics. The particle/powder metals can be compacted and fired (sintered) to 100% density, but the times involved for ceramics made it unviable for most commercial use. The times were on the order of days or weeks at temperatures above 2400* F. This was for aluminum oxide, and I realize that zirconium oxide may be faster, but, considering the cheapness of Al2O3, I'm guessing part of the cost of ZrO is the high temp and long time required for processing. This issue of porosity in ceramics is why I doubt the edge can be sharper than steel. Its like having carbide tearout, but the carbides are removed for you when the steel is made, so the dips and voids show up when the edge is formed. Possible a good slicing edge though.

The new Kyocera models I was looking at on Youtube have the corners and tips rounded for durabilities sake I suppose. If the tips of all my kitchen knives had a 1/4" radius, I wouldnt have to worry about broken tips. There are some drop tests on youtube that show the knives wont break or shatter when they are dropped from counter or table height. However, try that test when the edge has a chip in it and the story may be different.
 
When I called the Kyocera USA office they told me that they did not recommend honing a ceramic blade to as small an angle as a steel blade. They suggested that would make it more susceptible to chipping. I did the colleague's chipped knife without a guide or angle measurement but I was shooting for around 20 degrees.

When new, my Kyocera ceramics would shave hair off my forearm but took significant pressure to do so. A Murray Carter steel knife will "brush" hair off with extremely slight pressure.

I am about to leave for the W&SS Forum's Bush Bash II wilderness gathering. When I return I'll see if I can borrow a micrometer and measure the thickness of a ceramic blade at the spine and behind the edge bevel.

DancesWithKnives
 
I've owned 3 Kyocera knives for over 10 years now. They don't cut meat well and you can't chop with them. The ceramic is so brittle that I've chipped one trying to slice hard-crusted bread.

Only good for vegetable prep work, but no better than any decent steel knife.
 
I wonder if the newer ones are more damage/chip resistant. My ceramics lab professor said the material used was transformation toughened zirconia. I have a chapter on it in my ceramics book I'll have to study on. Basically, the stress at the tip of the crack causes a phase change, blunting the crack tip and taking some of the energy that would normally be used to propogate the crack.
 
The plus is that the blades are extremely hard and hold an edge about 5 times longer than a steel blade.

Now for the minus. They are brittle. They chip and break easily, even from dropping them on the floor. Because they are brittle You can't apply a normal bevel angle to them or the edges will chip. So they will always be duller than a steel knife. They are hard to sharpen because of the extreme hardness. They are too light in weight from many people. Also, the blades are shorter than comparable steel knives. That makes them inefficient. Efficiency isn't a big issue in a home kitchen to be fair but they are inefficient.

Personally, I think they are probably the worst examples of kitchen knives in the industry. I rarely rail against knives in this manner but I'm passionately opposed to ceramic blades. I'm not picking on Kyocera, just the blades.
 
If you use ceramic knives as intended, they are great.
I like to be able to sharpen my own knives so it's steel for me.
 
pvicenzi said:
Can you batton them?
Click to expand...


Absolutely you can.......once. :)

I had a Kyocera ceramic as well and my experiences were similar to others mentioned already. It was great cutting softer materials and food didn't seem to stick as much to the blade after being cut. I was actually get in to a routine using it then....I dropped it and that was that.
 
Mine is long gone, but recall the edge OTB as well one that I handled several years later…being obtuse, somewhat dull and would not shave arm hair. I don’t believe a ceramic blade can be thinned or support an acute edge as well as a steel blade…it would likely make an already brittle knife even more fragile and chippier. Sans my hard contact knives (cleaver,boning), my other knives are thinner and sharper. I can easily shave arm hair with my general purpose knives and beyond with my dedicated slicers.

I think they are made via somesort of high pressure compression press. It seems as though they are held together under high tension, but fail once the tension is compromised. The older ones were notorious for shattering like glass if dropped, loosing thier tips. Mine went like a windshield; the chipped evolve into a stress crack and the blade just snapped.

Personally, my experiences with it was so bad that I won’t go near one ever again.
 
To me, they seem to be the epitome of "takes a lousy edge and holds it forever". The folks I'm having the discussion with seem to think the edge can be made sharper and they cut better, hold an edge longer, and dont transfer flavors. I think the flavor transfer thing is way overblown. I will say that sometimes I can taste iron from cutting some foods with a carbon steel blade, but most kitchen knives are stainless. I almost lost my **** when they said that a ceramic knife's grains are so small that they are smooth, while the processing of stainless steel leaves small holes in the blades. I dont think its possible to make a statement related to knives that is any more bassackwards. Looks like I may be arguing w/ Kyocera's marketing department. So basically, based on what you all have experienced, its like I was saying. They hold an edge longer, unless you count the chipping, and are a lot more corrosion resistant. They are not tougher by any stretch of the imagination, thereby preventing them from having thinner angles/blades and based on the NIB edges from the makers, are not sharper than steel knives. Got it.
 
I think everybody in this forum is heavily into sharpening their knives, so any knive that does not need sharpening will get a thumbs down -- not that I'm a fan of ceramic knives. Now, if they ever invent a knive as sharp as you can get a straight razor, that doesn't lost its edge, ever, what the heck would we do with our time?
 
ziggy925 said:
I think everybody in this forum is heavily into sharpening their knives, so any knive that does not need sharpening will get a thumbs down -- not that I'm a fan of ceramic knives. Now, if they ever invent a knive as sharp as you can get a straight razor, that doesn't lost its edge, ever, what the heck would we do with our time?
Click to expand...

Not only that, but sharpening knives is a great way to get through those boring staff meetings.
 
"takes a lousy edge and holds it forever" is spot on. I don’t believe you can sharpen a ceramic with anything less than diamonds. Doing it un-powered with some sort of course grit diamond hone would likely take forever and leave deep scratches. Supposedly, those scratches act like mini fault or fracture lines and need to be polished out with progressively finer grits via a lapping machine.

Unless you’re cutting a lot of acidic foods and don’t (or use saltwater to) wash it off after using it… whatever additional imperviousness to staining, rust, and transferring flavor it may have over stainless steel is fluff.

I’m not one to sharpen my knives excessively or without reason….well….I don’t like to very often…..well….ok…rubbing a piece of metal against a muddy rock is fun.
 
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