How to sharpen a ceramic knife at home?

Superhard alloys based on metal and ceramics were created by scientists of the USSR Academy of Sciences more than fifty years ago for the manufacture of gas turbine blades, drilling tool crowns, rib prostheses, individual segments of the spine, jaws, bones of the musculoskeletal system, tools for processing heavy-duty metals, dentures and some other products.

The composition of new superhard alloys included metals (zirconium, cobalt, vanadium, aluminum, chromium, nickel, molybdenum, titanium) and ceramic components (silicon carbide and aluminosilicate, boron). An alloy of non-miscible components (molten metal and silicates) was obtained by sintering in a diamond tube an explosive wave of fine zirconium powder, silicate sand and alloying impurities in an atmosphere of pure oxygen at a temperature of more than + 1500 ° C and an overpressure of more than 200 atmospheres.

Today, rusting and maintenance-intensive steel cutlery has been replaced by ceramic cutlery with a blade made of extruded amorphous zirconium carbide or zirconia. Let's take a quick look at their merits and demerits.

Ceramic knives have the following advantages:

• sharpness - the perfectly sharpened surface of the blade allows you to quickly and easily cut fresh meat and fish, butcher carcasses of birds; it is especially convenient to use for preparing a large number of dishes in a short time in cafes, canteens, restaurants;
• the zirconium knife does not need to be sharpened daily;
• a thin film of zirconium oxide on the blade protects products from interacting with metal;
• food residues and grease do not adhere to the smooth surface of the cutting edge;
• a sharp knife does not require the use of excessive efforts, the likelihood of cuts on the fingers decreases;
• an attractive-looking metal-ceramic dagger can be used for cutting meat, cake, pudding, pineapple, watermelon and other products at the festive table;
• the zirconium knife does not lose its sharpness when exposed to high temperatures;
• the knife can be easily washed off from food debris with soapy water.

This product has the following disadvantages:

• fragile blade - if dropped from a great height onto tiles or concrete, the blade of the blade may split;
• sharpening of a cermet knife is possible only on a diamond-coated bar;
• it is very inconvenient to cut a large watermelon or pineapple with a short blade no more than 18 cm long;
• after cutting containing colored fruits and root crops (beetroot, dill), the blade must be rinsed with water;
• with a metal-ceramic knife, you cannot cut frozen meat and chop bones;
• the ceramic blade must not cut food on a worktop made of stone, polycarbonate, or doped plastic.

A slight inconvenience when using a knife with a ceramic zirconium blade sharpened on one side is a shift (sliding) towards the flat edge when cutting fluffy soft products (pudding, mousse, jelly, jelly, margarine, butter, cake, and others). A ceramic knife from a Japanese manufacturer of classic shape has a flat blade sharpened on one side.

In Europe, this type of blade due to the difficulty of restoring sharpness on double-sided roller sharpeners not widely adopted. For this reason, branches and subsidiaries of a Japanese and Chinese manufacturer in Europe produce zirconium cutlery knives with a wedge-shaped cut, sharpened symmetrically on both sides.

A blade sharpened in this way has the following advantages over a one-sided one:

• it is equally convenient for "right-handed" and "left-handed" people to use it;
• a double-beveled blade wears out more slowly;
• a double-sided blade, with a loss of sharpness, is much easier to sharpen on a diamond disc or on a "zero" diamond skin.

Given the special hardness of the blade made of zirconium, it can be sharpened with a diamond tool in one of the following ways:

• on a special sharpener;
• on a diamond wheel;
• in a workshop on professional equipment.

According to experts, taking into account the ratio of price and quality, the most widespread are the following sharpeners made in Japan for straightening the blades of zirconium knives:

• mechanical sharpener Kyocera DS-20 (Japan);
• electric sharpener Kyocera DS-50 (Japan, AA batteries);
• sharpener Kasumi 33001 (Japan, 2 compartments for zirconium and regular steel knives);
• electric machine for stage-by-stage sharpening of the blade Chef's Choice 316 (China, but under the license of Japan);
• TM Börner (Germany under license from Japan, double-sided bar for quick sharpening of a double-sided blade).

To restore the sharpness of a zirconium blade at home, you can use a corundum whetstone, a mechanical sharpener, diamond skin and diamond paste. Using a sharpener with an electric drive (mains or batteries) by an "curved" inexperienced craftsman can irreparably spoil the shape of the blade.The correctly sharpened edge of the blade when viewed in reflected light at a slight angle (up to 15 °) should be matt without shiny scratches, streaks and bright pointsek.

When sharpening a sintered zirconium kitchen blade with a single-sided blade, first sharpen the side that protrudes with a wedge until a uniform burr forms along the length of the cutting edge along the entire length. Then the blade is turned over to the opposite and the burr is ground until the surface is leveled. With double-sided sharpening, the blade is sharpened on one side until burrs appear, then the knife is turned over and sharpened in exactly the same way.

To sharpen a zirconium kitchen dagger on a diamond wheel, you must first purchase two diamond-coated wheels, namely:

• with a grain of 80 microns for rough processing;
• with 40 µm grit for final sanding.

It is necessary to sharpen the ceramic blade at low revolutions of the diamond wheel, constantly moving the knife along the grinding wheel in smooth circular motions, gradually reducing the pressure when approaching the edge of the blade. To sharpen the reverse side, turn the blade over and repeat the processing.

The most laborious method is sharpening a cermet knife with diamond paste by hand. To do this, you need to additionally purchase a wide leather belt or a wooden block of oak (beech). One end of the strap is securely attached to a wall or tabletop using a hook or screw. The diamond paste is spread evenly over the surface of the leather belt and tightened with the left hand. The knife is taken in the right hand and with little effort move the blade back and forth along the belt, slightly pressing it to the surface.

After each pass, the blade is turned over to the opposite side. In the process of work, you need to follow so that the blade is strictly parallel to the belt surface. If this condition is not met, you can spoil the shape of the thin edge of the blade and irrevocably ruin the kitchen cutter. In the process of work, you need to be extremely careful not to cut your hands.

The zirconium blade of the knife is resistant to high temperatures, much stronger than corundum and second only to diamond in hardness. With intensive use in the kitchen in canteens, cafes, restaurants, even with strict adherence to the rules of use and with careful handling, a razor-sharp knife blade loses its properties, it must be sharpened. The easiest way to restore sharpness at home is with a special device - a sharpener. The advantages of using this fixture are as follows:

• adequate price of licensed sharpeners;
• restoration of the correct angle of sharpening of the blade;
• guarantee of sharpness and safety of use;
• no special skills or knowledge are required to use the sharpener.

Cheap roller sharpeners with victorious linings and corundum inserts (made in China) for sharpening sintered knives are strictly not recommended. The rollers will leave deep scratches and chips on the surface of the blade. After processing a metal-ceramic knife blade that has lost its sharpness with such a "Chinese sharpening", it most often deteriorates irrevocably, an expensive knife has to be thrown away and bought a new one.

You can sharpen a zirconium knife blade using musat - a rod made of diamond and corundum chips with titanium microcrystals and magnetized fine cobalt. The magnetized sharpening tool attracts sawdust from the surface of the blade during the sharpening process. As a result, the sharp edge of the sharpened cut is perfectly smooth without burrs and small scratches.

This is the most difficult method of restoring the sharpness of a zirconia blade. Sharpening the blade using this method requires a great deal of experience and jewelry skill from the master. During operation, the blade should be moved parallel to the surface of the sharpener with slight pressure at an angle of no more than 3-5 °. In order not to spoil the shape of the blade, when the bar approaches the edge, the pressure on the knife must be loosened. Before starting work, the bar must be moistened with soapy water. It is not recommended to use oil for the following reasons:

• the oiled knife begins to slide along the surface of the bar, this moment increases the processing time of the kitchen cutter;
• Grease from the blade can get onto the handle, increasing the risk of injury when sharpening by slipping the hand from the handle onto the blade.

It is recommended to cover the linoleum surface in the kitchen near the countertop, on which a knife with a zirconium blade is used, with a rubber mat or a piece of cauliflower. Such a preventive measure will save a rather expensive and fragile blade from destruction if it accidentally falls to the floor. When restoring the sharpness of a zirconium blade by hand using diamond powder or a wooden block and a "zero" diamond skin, do not press the knife blade against the working surface of the improvised sharpener with excessive force.

Instead of the expected acceleration of the blade sharpening process, the opposite effect is most often obtained - the cutting surface of the blade is covered with rough scratches, for smoothing which requires subsequent grinding and polishing for a long time. When using an electrically driven machine blade and diamond discs for edge sharpening, do not hold the knife in one place. Otherwise, deep longitudinal grooves or teeth and pits appear on the cutting edge of the blade. It is almost impossible to fix this mistake; you will have to buy a new knife.

For information on how to sharpen a ceramic knife yourself, see the video below.