Zirconia Ceramic Parts

Zirconia ceramic is white, yellow or gray when it contains impurities, generally contains HfO2, and is not easy to separate. There are three crystalline states of pure ZrO2 under normal pressure. The production of Zirconia ceramic parts requires the preparation of powders with high purity, good dispersibility, ultra-fine particles and narrow particle size distribution. There are many preparation methods for zirconia ultra-fine powder. The purification of zirconia mainly includes chlorination and thermal decomposition, alkali metal Oxidative decomposition method, lime melting method, plasma arc method, precipitation method, colloid method, hydrolysis method, spray pyrolysis method, etc.

Zhongwei Precision is committed to providing domestic and foreign customers with advanced ceramics with high strength, high toughness, wear resistance, corrosion resistance and high temperature resistance. It is a high-tech enterprise integrating R&D, production and sales of industrial precision advanced ceramic products in the field of precision ceramics. With a variety of modern high-precision equipment, it has independently realized the completion of the entire production process of ceramic parts from ceramic powder preparation, green body molding, high temperature sintering to ceramic material finishing.

Product Description

1. Implementation standards: the company strictly implements ISO9001 certification, and the products have passed ROHS, FDA EU certification, etc.

2. Product material standards: ISO, GB, ASTM, SAE, EN, DIN, BS, AMS, JIS, ASME, DMS, TOCT, GB

3. Main processes: grouting, injection molding, tape casting, isostatic pressing, 3D printing

4. Available materials for ceramics:

It mainly produces finished ceramic rods, ceramic tubes, ceramic rings, ceramic plates, ceramic suction cups, ceramic blades and other special-shaped ceramic structures. The main ceramic materials are alumina, zirconia, silicon carbide, silicon nitride, and aluminum nitride ceramics. High temperature resistance, wear resistance, corrosion resistance, acid and alkali resistance, anti-magnetic, pressure resistance. And 3D printing, etc. are customized according to customer requirements.

Combined tube, its high wear resistance effectively resists material wear and impact.

Product Category and Production Process

Pure ZrO2 is white, yellow or gray when it contains impurities, and generally contains HfO2, which is not easy to separate. The world's proven zirconium resources are about 19 million tons, and zirconia is usually obtained by purifying zirconium ore. There are three crystal states of pure ZrO2 at normal pressure: monoclinic zirconia (m-ZrO2), tetragonal zirconia (t-ZrO2) and cubic (Cubic) zirconia (c-ZrO2). Types exist in different temperature ranges and can be converted into each other:

Temperature Density

Monoclinic zirconia (m-ZrO2) <950℃ 5.65g/cc

Square zirconia (t-ZrO2) 1200-2370℃ 6.10g/cc

Cubic Zirconia (c-ZrO2) >2370℃ 6.27g/cc

The above three crystalline states have different physical and chemical properties. In order to obtain the desired crystalline form and performance in practical applications, different types of stabilizers are usually added to make different types of Zirconia ceramic parts, such as partially stabilized zirconia (partially stabilized zirconia, PSZ), when the stabilizer is CaO, MgO, Y2O3, it is expressed as Ca-PSZ, Mg-PSZ, Y-PSZ, etc. respectively. The tetragonal zirconia composed of metastable t-ZrO2 is called tetragonal zirconia polycrysta (TZP). When the added stabilizers are Y2O3 and CeO2, they are expressed as Y-TZP, Ce-TZP, etc. respectively.

1. Powder preparation

The production of zirconia ceramics requires the preparation of powders with high purity, good dispersion properties, ultra-fine particles and narrow particle size distribution. There are many preparation methods for zirconia ultra-fine powder. The purification of zirconia mainly includes chlorination and thermal decomposition, alkali metal Oxidative decomposition method, lime melting method, plasma arc method, precipitation method, colloid method, hydrolysis method, spray pyrolysis method, etc. Powder processing methods include co-precipitation method, sol-gel method, evaporation method, supercritical synthesis method, microemulsion method, hydrothermal synthesis method, network and vapor deposition method.

2. Production process

(1) Forming

The molding of zirconia ceramics includes dry pressing molding, isostatic pressing molding, grouting molding, hot die casting molding, tape casting, injection molding, plastic extrusion molding, colloidal solidification molding, etc. The most widely used are injection molding and dry pressing.

①Grout molding

The molding process of grouting includes physical dehydration process and chemical coagulation process. Physical dehydration removes the water in the slurry through the capillary action of the porous gypsum mold. The chemical coagulation process is because Ca2+ generated by the dissolution of CaSO4 on the surface of the gypsum mold improves the slurry The ionic strength in the material causes the flocculation of the slurry. Under the action of physical dehydration and chemical coagulation, the ceramic powder particles are deposited on the gypsum mold wall. Grouting is suitable for the preparation of large-scale ceramic parts with complex shapes, but the quality of the green body, including shape, density, strength, etc., is poor, the labor intensity of workers is high, and it is not suitable for automated operations.

②Hot pressure injection molding

Hot pressure injection molding is to mix ceramic powder with binder (paraffin) at a relatively high temperature (60~100 ° C) to obtain a slurry for hot die casting, and the slurry is injected into the metal mold under the action of compressed air to keep the Press cooling, demoulding to obtain a wax blank, the wax blank is dewaxed under the protection of inert powder to obtain a green body, and the green body is sintered at high temperature to become porcelain. The green body of hot press injection molding has accurate size, uniform internal structure, less mold wear, high production efficiency, and is suitable for various raw materials. The temperature of the wax slurry and the mold needs to be strictly controlled, otherwise it will cause under injection or deformation, so it is not suitable for manufacturing large parts, and the two-step firing process is complicated and energy consumption is high.

③ Tape casting

Tape casting is to fully mix ceramic powder with a large amount of organic binders, plasticizers, dispersants, etc. to obtain a flowable viscous slurry, add the slurry to the hopper of the casting machine, and use a scraper to control the thickness. It flows out to the conveyor belt through the feeding nozzle, and the film blank is obtained after drying. This process is suitable for the preparation of film materials. In order to obtain better flexibility, a large amount of organic matter is added, and the process parameters are required to be strictly controlled, otherwise it will easily cause defects such as peeling, streaks, low film strength or difficult peeling. The organic matter used is toxic and will cause environmental pollution, and a non-toxic or less toxic system should be used as much as possible to reduce environmental pollution.

(2) Degreasing and degumming

In addition to the forming technology based on dry pressing, the products formed by other processes must be degreasing and degummed before being sintered in the furnace, because other processes except dry pressing will add a certain proportion of zirconium powder to the forming process. Plasticizers, these plasticizers must be removed after the product is formed, otherwise it will have a serious impact on the quality of the sintered product. Plasticizers are mainly composed of paraffin and other polymer materials. These materials are required to exhibit good plasticity and fluidity at a certain temperature, and have certain toughness and strength at room temperature.

(3) Sintering

The sintering methods that can be used for Zirconia ceramic parts are usually:

①Pressureless sintering ②Hot pressing sintering and reactive hot pressing sintering ③ Hot isostatic pressing (HIP) ④ Microwave sintering ⑤ Ultra-high pressure sintering, ⑥ Spark plasma sintering (SPS) ⑦ In-situ pressure forming sintering, etc. Pressureless sintering is often used.

Process After Sintering

Processing equipment: equipped with CNC engraving machine, centerless grinding, internal and external cylindrical grinding, surface grinding, CNC lathe machining center, wire cutting, turning, milling, grinding and other high-precision production and testing equipment.

Moulds and Inspection Fixtures

1. Mold service life: usually semi-permanent. (except for lost foam).

2. Mold delivery time: 10-25 days, (according to product structure and product size).

3. Tooling and mold maintenance: Zhongwei is responsible for precision parts.

Quality Control

1. Quality control: the defective rate is less than 0.1%.

2. Samples and trial run will be 100% inspected during production and before shipment, sample inspection for mass production according to ISDO standards or customer requirements.

3. Test equipment: roundness measuring instrument, three-coordinate measuring instrument, image coordinate measuring instrument, Hexagon three-coordinate measuring instrument, image measuring instrument, density measuring instrument, smoothness measuring instrument, micro Vickers hardness tester.

Application

In terms of structural ceramics, Zirconia ceramic parts are widely used in the field of structural ceramics because of their high toughness, high flexural strength and high wear resistance, excellent thermal insulation properties, and thermal expansion coefficient close to steel. Mainly include: Y-TZP grinding balls, dispersing and grinding media, nozzles, ball valve seats, zirconia molds, miniature fan shafts, fiber optic pins, fiber optic sleeves, drawing dies and cutting tools, wear-resistant knives, clothing buttons, Cases and straps, bracelets and pendants, ball bearings, light bats for golf balls, and other room temperature wear-resistant parts.

In terms of functional ceramics, its excellent high temperature resistance is used as induction heating tubes, refractory materials, and heating elements. Zirconia ceramics have sensitive electrical performance parameters and are mainly used in oxygen sensors, solid oxide fuel cells (SOFC) and high temperature heating elements. ZrO2 has a high refractive index (N-21^22), adding certain coloring elements (V2O5, MoO3, Fe2O3, etc.) to the ultra-fine zirconia powder, it can be made into colorful translucent polycrystalline ZrO2 materials , shining like a natural gemstone with brilliant and colorful light, it can be made into a variety of decorations. In addition, zirconia is being widely used in thermal barrier coatings, catalyst carriers, medical care, health care, refractories, textiles and other fields.