Ceramic knife

Last updated
A ceramic knife. Zayka-apache.jpg
A ceramic knife.

A ceramic knife is a knife with a ceramic blade typically made from zirconium dioxide (ZrO2; also known as zirconia), [1] rather than the steel used for most knives. Ceramic knife blades are usually produced through the dry-pressing and firing of powdered zirconia using solid-state sintering. The blades typically score 8.5 on the Mohs scale of mineral hardness, compared to 4.5 for normal steel and 7.5 to 8 for hardened steel [ citation needed ] and 10 for diamond. The resultant blade has a hard edge that stays sharp for much longer than conventional steel blades. However, the blade is brittle, subject to chipping, and will break rather than flex if twisted. The ceramic blade is sharpened by grinding the edges with a diamond-dust-coated grinding wheel.

Contents

Zirconium oxide

A ceramic knife made from blackened zirconia, super heated under pressure. Dalstrong Ceramic KnifeM.png
A ceramic knife made from blackened zirconia, super heated under pressure.

Zirconium oxide is used due to the fact it exists in several different forms. Zirconium can be monoclinic, tetragonal or cubic in form. Cooling to the monoclinic phase after sintering causes a large volume change, which often causes stress fractures in pure zirconia. Additives such as magnesia, calcia and yttria are used in manufacturing the knife material to stabilize the high-temperature phases and minimize this volume change. The highest strength and toughness is produced by the addition of 3  mol% yttrium oxide yielding partially stabilized zirconia. This material consists of a mixture of tetragonal and cubic phases with a bending strength of nearly 1,200 MPa (170,000 psi). Small cracks allow phase transformations to occur, which essentially close the cracks and prevent catastrophic failure, resulting in a relatively tough ceramic material, sometimes known as TTZ (transformation-toughened zirconia).

Properties

Special ceramic jackknife Keramikklappmesser.jpg
Special ceramic jackknife

Ceramic knives are substantially harder than steel knives, will not corrode in harsh environments, [2] are non-magnetic, and do not conduct electricity at room temperature. Because of their resistance to strong acid and caustic substances, [3] and their ability to retain a cutting edge longer than steel knives, [2] ceramic knives are suitable for slicing boneless meat, vegetables, fruit and bread. Since ceramics are brittle, blades may break if dropped on a hard surface, although improved manufacturing processes have reduced this risk. They are also unsuitable for chopping through hard foods such as bones or frozen foods, and for applications which require prying, which may cause breaking or chipping. Several brands offer either a black-coloured or a designed blade made through an additional hot isostatic pressing step, which increases toughness.

Sharpening and general care

A diamond dust sharpener with cradle for a ceramic knife. Dalstrong Edgelast Sharpener.png
A diamond dust sharpener with cradle for a ceramic knife.

Unlike a steel blade that benefits from regular honing and resharpening in order to keep a sharp edge, a much harder ceramic blade will stay sharp and retain its cutting edge for much longer—at least ten times longer according to tests on a particular knife. [4] However, the hardness of the ceramic material also makes it difficult to resharpen. [5] Consequently, although a ceramic knife does not need regular sharpening in the same way as steel, when its blade eventually becomes blunt or chips specialized sharpening services are required for the ceramic edge. [6]

Related Research Articles

<span class="mw-page-title-main">Ceramic</span> Inorganic, nonmetallic solid prepared by the action of heat

A ceramic is any of the various hard, brittle, heat-resistant, and corrosion-resistant materials made by shaping and then firing an inorganic, nonmetallic material, such as clay, at a high temperature. Common examples are earthenware, porcelain, and brick.

<span class="mw-page-title-main">Zirconium dioxide</span> Chemical compound

Zirconium dioxide is a white crystalline oxide of zirconium. Its most naturally occurring form, with a monoclinic crystalline structure, is the mineral baddeleyite. A dopant stabilized cubic structured zirconia, cubic zirconia, is synthesized in various colours for use as a gemstone and a diamond simulant.

<span class="mw-page-title-main">Differential heat treatment</span> Technique used in heat treating

Differential heat treatment is a technique used during heat treating of steel to harden or soften certain areas of an object, creating a difference in hardness between these areas. There are many techniques for creating a difference in properties, but most can be defined as either differential hardening or differential tempering. These were common heat treatment techniques used historically in Europe and Asia, with possibly the most widely known example being from Japanese swordsmithing. Some modern varieties were developed in the twentieth century as metallurgical knowledge and technology rapidly increased.

<span class="mw-page-title-main">Blade</span> Sharp cutting part of a weapon or tool

A blade is the portion of a tool, weapon, or machine with an edge that is designed to puncture, chop, slice or scrape surfaces or materials. Blades are typically made from materials that are harder than those they are to be used on. Historically, humans have made blades from flaking stones such as flint or obsidian, and from various metal such as copper, bronze, and iron. Modern blades are often made of steel or ceramic. Blades are one of humanity's oldest tools, and continue to be used for combat, food preparation, and other purposes.

An abrasive is a material, often a mineral, that is used to shape or finish a workpiece through rubbing which leads to part of the workpiece being worn away by friction. While finishing a material often means polishing it to gain a smooth, reflective surface, the process can also involve roughening as in satin, matte or beaded finishes. In short, the ceramics which are used to cut, grind and polish other softer materials are known as abrasives.

<span class="mw-page-title-main">Japanese kitchen knife</span> Type of knife used for food preparation

A Japanese kitchen knife is a type of a knife used for food preparation. These knives come in many different varieties and are often made using traditional Japanese blacksmithing techniques. They can be made from stainless steel, or hagane, which is the same kind of steel used to make Japanese swords. Most knives are referred to as hōchō or the variation -bōchō in compound words but can have other names including -kiri. There are four general categories used to distinguish the Japanese knife designs: handle, blade grind, steel, and construction.

<span class="mw-page-title-main">Grind</span> Cross sectional shape of a blade in a plane normal to its edge

A blade's grind is its cross-sectional shape in a plane normal to the edge. Grind differs from blade profile, which is the blade's cross-sectional shape in the plane containing the blade's edge and the centre contour of the blade's back. The grind of a blade should not be confused with the bevel forming the sharpened edge; it more usually describes the overall cross-section of the blade, not inclusive of the beveled cutting edge which is typically of a different, less acute angle as the bevel ground onto the blade to give it a cross-sectional shape. For example, the famous Buck 110 hunting knife has a "hollow ground" blade, with concave blade faces, but the cutting edge itself is a simple, flat-ground bevel of lesser angle. It would be difficult, if not impossible, to put a "hollow grind" onto the actual cutting edge of the blade itself, which is a very narrow and small bevel.

<span class="mw-page-title-main">Kitchen knife</span> Knives intended for use in the process of preparing food

A kitchen knife is any knife that is intended to be used in food preparation. While much of this work can be accomplished with a few general-purpose knives – notably a large chef's knife, a tough cleaver, a small paring knife and some sort of serrated blade – there are also many specialized knives that are designed for specific tasks. Kitchen knives can be made from several different materials.

In cooking, a chef's knife, also known as a cook's knife, is a cutting tool used in food preparation. The chef's knife was originally designed primarily to slice and disjoint large cuts of beef. Today it is the primary general-utility knife for most Western cooks.

<span class="mw-page-title-main">Glass knife</span>

A glass knife is a knife with a blade made of glass, with a fracture line forming an extremely sharp cutting edge.

<span class="mw-page-title-main">Sharpening</span> Creating or refining the edge of a cutting tool

Sharpening is the process of creating or refining the edge joining two non-coplanar faces into a converging apex, thereby creating an edge of appropriate shape on a tool or implement designed for cutting. Sharpening is done by removing material on an implement with an abrasive substance harder than the material of the implement, followed sometimes by processes to polish/hone the sharp surface to increase smoothness.

<span class="mw-page-title-main">Knife making</span> Process of manufacturing a knife

Knife making is the process of manufacturing a knife by any one or a combination of processes: stock removal, forging to shape, welded lamination or investment cast. Typical metals used come from the carbon steel, tool, or stainless steel families. Primitive knives have been made from bronze, copper, brass, iron, obsidian, and flint.

<span class="mw-page-title-main">Ceramic engineering</span> Science and technology of creating objects from inorganic, non-metallic materials

Ceramic engineering is the science and technology of creating objects from inorganic, non-metallic materials. This is done either by the action of heat, or at lower temperatures using precipitation reactions from high-purity chemical solutions. The term includes the purification of raw materials, the study and production of the chemical compounds concerned, their formation into components and the study of their structure, composition and properties.

<span class="mw-page-title-main">Knife sharpening</span>

Knife sharpening is the process of making a knife or similar tool sharp by grinding against a hard, rough surface, typically a stone, or a flexible surface with hard particles, such as sandpaper. Additionally, a leather razor strop, or strop, is often used to straighten and polish an edge.

<span class="mw-page-title-main">Diamond tool</span>

A diamond tool is a cutting tool with diamond grains fixed on the functional parts of the tool via a bonding material or another method. As diamond is a superhard material, diamond tools have many advantages as compared with tools made with common abrasives such as corundum and silicon carbide.

<span class="mw-page-title-main">Diamond blade</span> Saw blade with diamond grit bonded to the cutting surface

A diamond blade is a saw blade which has diamonds fixed on its edge for cutting hard or abrasive materials. There are many types of diamond blade, and they have many uses, including cutting stone, concrete, asphalt, bricks, coal balls, glass, and ceramics in the construction industry; cutting semiconductor materials in the semiconductor industry; and cutting gemstones, including diamonds, in the gem industry.

<span class="mw-page-title-main">Honing steel</span> Rod of steel used to restore keenness to dulled blades

A honing steel, sometimes referred to as a sharpening steel, whet steel, sharpening stick, sharpening rod, butcher's steel, and chef's steel, is a rod of steel, ceramic or diamond-coated steel used to restore keenness to dulled blade edges. They are flat, oval, or round in cross-section and up to 30 centimetres (1 ft) long. The steel and ceramic honing steels may have longitudinal ridges, whereas the diamond-coated steels are smooth but embedded with abrasive diamond particles.

Zirconia toughened alumina is a ceramic material comprising alumina and zirconia. It is a composite ceramic material with zirconia grains in the alumina matrix.

<span class="mw-page-title-main">Yttria-stabilized zirconia</span> Ceramic with room temperature stable cubic crystal structure

Yttria-stabilized zirconia (YSZ) is a ceramic in which the cubic crystal structure of zirconium dioxide is made stable at room temperature by an addition of yttrium oxide. These oxides are commonly called "zirconia" (ZrO2) and "yttria" (Y2O3), hence the name.

References

  1. "Frequently Asked Questions | Ceramic Advantage | Ceramic Knives | Kyocera Advanced Ceramics". Archived from the original on 2015-12-10. Retrieved 2015-12-20.
  2. 1 2 The Ceramic Society of Japan (31 July 2012). "22.1 Ceramic Knife, Grater, Slicer and Scissors (first commercialised 1984)". In Yoshihiko Imanaka (ed.). Advanced Ceramic Technologies & Products. Springer Science & Business Media. pp. 529–530. doi:10.1007/978-4-431-54108-0_22. ISBN   978-4-431-53913-1. S2CID   136842009.
  3. Wilson, Bee (22 Jun 2012). "At the cutting edge: ceramic knives". The Telegraph. Retrieved 27 July 2016.
  4. "Kyocera catalog" (PDF). 6 April 2012. Archived from the original on 2015-10-13. According to the Cutlery and Allied Trades Research Association (CATRA), an independent testing organization, recent [November 2005] tests show that the life of a Kyocera ceramic blade without resharpening is approximately 10 times that of a typical steel blade.
  5. Wolfgang Puck (8 April 2007). Wolfgang Puck Makes It Easy: Delicious Recipes for Your Home Kitchen. Thomas Nelson. pp. 269–. ISBN   978-1-4185-7093-4.
  6. Sur La Table; Sarah Jay (21 October 2008). Knives Cooks Love: Selection. Care. Techniques. Recipes. Andrews McMeel Publishing. pp. 12–. ISBN   978-0-7407-7002-9.