Primarily used in kitchen cutlery, ceramic blades are beginning to make their way into other edged tools. Recently, the ceramic pocket knife crept onto the everyday carry market, challenging their steel counterparts. Will, they ever replace steel? Probably not. But, they do out perform steel knives in a number of important areas.
Ceramics are inorganic and nonmetallic materials that resist compression but often lack tensile strength. Their fragile nature would make them seem impractical for use in any sort of tool application. The ceramics that manufacturers use for knife blades, have little in common with the brittle, clay-based ceramic used in figurines.
The modern material of choice for ceramic blades is zirconium oxide – or zirconia. This material is nonporous, and it is nonconductive of both heat and electricity. Knife manufacturers combine pure powdered zirconia in its base phase with one or more of several possible additives. The additives stabilize the ceramic product at high temperatures.
Once stabilized, the material is sintered into the shape of the blade before being sharpened. Without the additives, the ceramic would shrink too much during cooling. Which would cause it to fracture or leave it susceptible to the same. Modern zirconia ceramic is one of the hardest blade materials available, though. It rates 8.5 on the Mohs scale, well above steel’s 4.5 rating and still harder than tool steel’s 7.5 to 8.
Blade Care and Use
Because zirconia is nonreactive, it will not corrode in the presence of chemicals and it won’t rust. The best way to clean the blade is with a mild dish detergent and plain old water. Being nonporous, ceramic blades provide microorganisms with no pockets in which to hide. Their surfaces stay cleaner, longer than steel knives do, and they require no oiling because they never oxidize.
However, ceramic blades do have drawbacks, one. being their tendency to chip at their edges. Modern zirconia ceramic is tough as steel on many levels, thanks to the various additives manufacturers use to strengthen them. They won’t shatter like earlier versions may have when dropped, but their thin edges are susceptible to microscopic chipping that can affect how they cut. When they reach this point, and it’s time for sharpening, ceramics reveal their other main nuisance.
Ceramic Blade Sharpening
The hardness of zirconia ceramic is a double-edged sword, so to speak. Their hardness enables ceramic blades to retain an edge many times longer than most steel blades can, but their inherent brittleness means their usefulness is limited. Hard materials such as bone cause the chips that can all but ruin the delicately fine edge of a ceramic knife, and prying actions are sure to break a ceramic blade.
Anyone who needs a knife only for occasional slicing of softer materials should be pleased to find an incredibly sharp edge whenever a ceramic folder is opened, though. Even under regular use, ceramic blades can keep cutting long past the time when a steel blade will need sharpening, so long as the materials are all relatively soft. When a ceramic knife does eventually need sharpening, though, the options for honing an edge are severely limited.
The only readily available materials capable of sharpening ceramic knives are diamonds. Most manufacturers use grinding stones encrusted with diamond dust to put an edge on their blades, but any industrial-diamond sharpening implement should suffice. These sharpeners will also smooth out small edge chips, but large chips will likely require a grinding stone to correct.
Quality Ceramic Folders
Stone River Gear – Ceramic Folder with Carbon Fiber Handle
This Stone River Gear offering has a thin profile, making it suitable for every day carry, and the blade stands up to the paper, cardboard and rope cutting that most of these knives have to do. The 2.625-inch, drop-point blade is made from a dense zirconium oxide alloy, and the whole package folds to a discrete 3.75 inches closed. Just keep its duties to slicing soft materials, and its razor-sharp cutting edge will far outlast a steel knife’s edge.
The carbon fiber handle that Stone River Gear uses lightens this knife’s load in a pack or as an EDC. Carbon fiber has seen use in the custom auto racing parts industry for years because it is lighter and stronger than steel in most respects. The blade and handle combination would defeat a metal detector, but the clip, screws and liner locking mechanism are all metallic (just like the rest of the knives on this list). Their purpose is defeating weight, not metal detectors.
Stone River Gear’s light little ceramic knife is a fine slicer right out of the box. Its edge does indeed outlast nearly any steel blade’s edge, but it will not last forever. The harder the use, the sooner it will need sharpening, but that time just won’t come nearly as soon as it will with steel. While it lasts, the factory edge on this blade will amaze the casual user, and should not fail to impress even the most jaded of knife collectors. We actually think the knife makes a great gentleman’s knife.
Boker – Anti-Grav
The Boker company was already one hundred years old when it became one of 19th-century Germany’s most prolific sword makers. Its sabers graced the battlefields of Europe until that weapon ceased to be useful or practical in combat situations. The company split into American and German divisions before World War II, and Boker USA has produced the lion’s share of the modern company’s knives ever since.
Boker is one of the few manufacturers currently making high quality folding ceramic knives. The Anti-Grav, one of Boker’s most popular ceramic EDCs, has a 3.3-inch, zirconia blade with a drop point and ambidextrous thumb studs for one-handed opening. The carbon fiber handle offers an ergonomic grip. And, the knife features a frame-lock mechanism that prevents accidental closures.
The Anti-Grav is an elegant example of lightweight ceramics. At just 2.1 ounces, it is barely noticeable as an EDC. It carries deeply when clipped to a pocket, and its thin profile lets it melt into the waistline when carried on a belt. Boker offers a sharpening service for those who struggle to replicate its incredibly sharp factory edge, but it will take a while to need that service under light, slicing-only use.
Schrade – SCH405
Schrade dates back to the early 1900s, when it was known as Imperial Schrade, but the longstanding knife company ceased to be in 2004. A rebranding saw a return of the name, though, and its parent company now operates under the Smith & Wesson umbrella of companies. Much like its stablemate, Old Timer — or competitor Gerber — the Schrade brand earns its bones making durable, affordable knives. These blades tend to see a lot of use because they are usually more expendable than more-expensive collector’s items.
Schrade’s ceramic knives, like its miniscule SCH405, give curious knife collectors the opportunity to try out one of these little slicers without making a large investment. The SCH405 features a spear point zirconia blade that is just 2.4 inches long. The blade also offers users a thumbhole for one-handed opening and a carbon fiber handle. The little folder is 5.6 inches long open, and just 3.2 inches closed. It also has a metallic belt clip and carries tip-down.
The SCH405 likely is not the one perfect knife for everyone to carry as an EDC. It cannot pry and it will not take much abuse. It is also not the sharpest ceramic blade available. However, as an entryway into the blade type, it just may be the perfect, precision-cutting backup to a more utilitarian EDC.
Is a Ceramic Knife Right for You?
Their ability to keep a razor-sharp edge for long periods of time make ceramics seem like a no-brainer blade material. However, they do have one major downfall: Their incredible hardness brings with it considerable susceptibility to fracture. Without additives, all ceramic blades would be prone to breaking. In fact, it’s a reputation which they earned soon after they entered the cutlery marketplace. The additives and manufacturing processes make these blades much tougher than their predecessors, but also more expensive.
When comparing ceramic knives, it is tempting to think that a cheaper version is just as good as more expensive models, but this is a rarity. The materials and the manufacturing processes of quality ceramic knives are all quite expensive, and knife makers must naturally pass those costs onto to the consumer if they are to make a profit. Expense is no guarantee of quality, of course, but tantalizingly low prices are telltale signs of fragility with these specialty blades.