Category: Basic Info

How to Prepare Zirconium Silicide Nanomaterials?

Introduction

Zirconium silicide is a steel gray orthorhombic shiny crystal. It is insoluble in water, mineral acids, and aqua regia, and soluble in hydrofluoric acid. Zirconium silicide is an excellent ceramic material with high hardness, high melting point, high electrical conductivity, high thermal conductivity, and excellent thermal shock resistance. Because of these advantages, it can be applied to structural materials or new engineering materials for high-temperature corrosive media.

Preparation

Zirconium silicide nanomaterial can be obtained by reacting a mixture of zirconium oxide powder, silicon powder and lithium in a proportioned amount at a high temperature in the absence of air. Specific steps are as follows:

(1) Add 5mmol zirconium dioxide, 5mmol silicon powder and 50mmol metallic lithium in a 20-milliliter stainless steel autoclave, then put the autoclave into an electric furnace.

2) Set the heating rate of the electric furnace to 10 °C per minute, and heat the electric furnace to 600 °C.

3) After the temperature was raised to 600°C, the temperature was maintained for 40 hours to ensure that the raw materials were fully reacted.

4) After the reaction was completed, naturally cool down the autoclave to room temperature, and then open the autoclave and take out the black deposit.

5) Wash the deposit with distilled water once, and then wash with dilute hydrochloric acid and absolute ethanol once respectively.

6) Filter the washed deposit, and then dry it in a vacuum drying oven at 60° C for 4 hours to obtain a zirconium silicide nanomaterial.

Zirconium Silicide Powder

The above reaction process is represented by the following equation:

ZrO2+Si+4Li=ZrSi+2Li2O

According to the quality of the prepared zirconium silicide nanomaterials and the quality of the used raw material zirconium dioxide, the method obtains that the yield of zirconium silicide is 85%.

Application

Zirconium silicide nanomaterial can be used to prepare a high-density ceramic matrix composite material: zirconium diboride-zirconium disilicide-tungsten carbide ceramic matrix composite material. This material is prepared from zirconium diboride powder, zirconium disilicide and tungsten carbide (purity >98.0%) using a two-step hot pressing sintering process. Wherein, the mass fraction of zirconium diboride powder is 75-90%, the mass fraction of zirconium disilicide is 10-15%, and the mass fraction of tungsten carbide is 0-10%. Adding a higher content of zirconium diboride to the ceramic matrix composite material is beneficial to improve the physicochemical properties of the composite material; adding this appropriate amount of zirconium disilicide to the ceramic matrix composite material can significantly reduce the sintering temperature for material preparation; the added tungsten carbide can promote anisotropic growth of grains inside the material.

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Zircon and Zircon Sand (Zr2SiO4)

Zircon sand, also known as zircon, is a mineral mainly composed of zirconium silicate (Zr2SiO4). Pure zircon is colorless and transparent crystal; depending on the origin, type, and quantity of impurities, zircon sand may appear in yellow, orange, red, brown, and other colors. The uniform Mohs hardness of zircon is 7-8, the refractive index is 1.93-2.01, and the melting point fluctuates within 2190-2420 ℃ with different impurities.

Chemical Composition

The main chemical composition of zircon is ZrO2 & SiO2, and a small amount of impurities such as Fe2O3, CaO, AI2O3, etc. The theoretical composition of zircon sand is ZrO2: 67.1%; SiO2: 32.9%. It is the only compound in the ZrO2-SiO2 system. But natural zircon sand only contains about 57~66% ZrO2.

Properties

Zircon is a mineral composed primarily of zirconium, silicon, and oxygen that crystallized out of magma when igneous rocks formed. It is the most important zirconium-bearing mineral – it is the most widely distributed, the most abundant, and the most types of zirconium minerals. Zircon belongs to the tetragonal crystal system, often in the form of well-developed cone-shaped small square cylinders, and also irregular granular. It is brittle and has a shell-like fracture. It is mostly symbiotic with ilmenite, rutile, monazite, xenotime, etc. in the coastal sand.

Zircon Sand

Application

Zircon is the main raw material for the preparation of zirconium, hafnium and various zirconium products. It is also a high-quality refractory material with high melting point, low thermal conductivity and small linear expansion coefficient, and is widely used in metallurgy, casting and other industries.

The addition of zircon to other materials can improve their performance. For example, adding zircon sand to synthetic cordierite can broaden the sintering range of cordierite without affecting its thermal shock stability; Adding zircon sand to high-alumina bricks to manufacture anti-stripping high-alumina bricks, the thermal shock stability is greatly improved; It can also be used to extract ZrO2.

More specific applications are as follows:

Refractory: zirconium refractory, such as zirconium corundum brick, zirconium refractory fiber;

Sand for casting mold in the foundry industry: molding sand for precision casting, precision enamel utensils;

Glass, metal: sponge zirconium;

Production of zirconium compounds: such as zirconium dioxide, zirconium oxychloride, sodium zirconate, potassium fluorozirconate, zirconium sulfate, etc.

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Separation of Zirconium and Hafnium by Solvent Extraction

Solvent extraction of zirconium and hafnium is one of the common methods for separating zirconium and hafnium. Compared with other zirconium and hafnium separation methods (such as pyrolysis separation and solvent extraction separation), this method has the advantages of large production capacity, simple process and easy to achieve continuously.

Principle

The extraction agents used for the separation of zirconium and hafnium mainly include ketone extractants, neutral phosphorus-containing extractants and amine extractants.

A commonly used ketone extractant is methyl isobutyl ketone (MIBK), which can form a neutral extract with hafnium thiocyanate and is preferentially extracted into the organic phase.

Methyl isobutyl ketone 3D ball
Methyl isobutyl ketone 3D ball. Source: Wikipedia

A typical neutral phosphorus-containing extractant is tributyl phosphate (TBP), which is preferentially extracted into the organic phase through the coordination of oxygen atoms in chemical bonds with zirconium metal atoms to form a neutral extract compound Zr(NO3)4•2TBP.

Ball and stick model of Tributyl phosphate
Ball and stick model of Tributyl phosphate. Source: Wikipedia

The commonly used amine extractant is trioctylamine (TOA). Trioctylamine forms an extract with zirconium ions in an acidic medium, and is preferentially extracted into the organic phase.

Process flow

There are three extraction processes: MIBK, TBP, and N235.

MIBK extraction

It uses ZrCI4 as raw material, adds water and NH4CNS ingredients. MIBK preferentially extracts hafnium, leaving a large amount of zirconium in the aqueous phase. This is the earliest extraction process used to separate zirconium and hafnium, and it is adopted by major producers of zirconium and hafnium such as the United States, France, Germany, and Japan.

TBP extraction

There are two aqueous feed systems for this process: nitric acid, and a mixed acid of nitric & hydrochloric acid. The former is to convert the product of zircon decomposed by alkali fusion method into nitric acid aqueous phase feed liquid, and use TBP to preferentially extract zirconium; the latter use Zr-CI4 as raw material, add water, nitric acid and hydrochloric acid as ingredients, and then use TBP to preferentially extract zirconium.

The separation coefficient of zirconium and hafnium in the TBP extraction process is large, and the number of extraction stages is small, and atomic-level zirconium oxide and hafnium oxide can be obtained at the same time. However, the water-phase feed liquid is highly corrosive, and the emulsification problem in the extraction process has not been completely solved, thus affecting its popularization and application.

N235 extraction

First, the zircon is decomposed by alkali fusion method, and the product is washed with water to remove silicon, and then leached with sulfuric acid to obtain a sulfuric acid solution of zirconium, and then the zirconium is preferentially extracted with N235. After washing, atomic-level zirconia containing hafnium <0.01% can be obtained. The hafnium in the raffinate is enriched to 50% to 70%, and then extracted by P204, and the zirconium and hafnium are further separated to obtain atomic energy level hafnium oxide containing more than 96% of hafnium.

This process has low material toxicity, light equipment corrosion, stable operation, and easy disposal of waste, so it is currently recognized as one of the best extraction processes.

Extraction equipment

There are two main types of extraction equipment, one is the extraction tower, and the other is the box-type mixer-settler. The former is used by the MIBK process, and the latter is used by TBP and N235 extraction process. The extraction tower occupies a small area and has a large production capacity. The box-type mixer-clarifier is simple in structure and stable in operation, and is generally made of acid-resistant materials such as plastic or plexiglass.

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3 Methods to Separate Zirconium & Hafnium

The two elements of zirconium and hafnium are symbiotic resources, which means that zirconium generally contains 0.5% to 2% of hafnium. However, the application of zirconium products in various industries requires high purity. For example, zirconium, which is a structural and cladding material for nuclear reactors, must contain less than 0.01% hafnium. In general, the metallurgical process of separating zirconium and hafnium is an important part of the zirconium metallurgical process.

The separation methods of zirconium and hafnium include pyrolysis separation, solvent extraction separation, and ion exchange separation. This article will briefly introduce these three separation methods.

Zirconium and Hafnium Pyrolysis Separation

Pyro separation is a method of separating zirconium and hafnium at high temperature or high pressure by using the difference in vapor pressure of zirconium and hafnium chloride. Zirconium and hafnium pyrolysis can replace the three production stages of extraction, calcination and chlorination in common separation methods. It has the characteristics of a short production process, high efficiency, low reagent cost and light pollution to the environment, and is a promising method for separating zirconium and hafnium.

The pyrolysis method is mainly realized by high-pressure rectification and molten salt rectification. High-pressure rectification is a process of directly separating zirconium and hafnium by using the difference in vapor pressure of Zrcl4 and HfCl4. Molten salt rectification is a process of separating zirconium and hafnium in a rectifying tower by using the difference in saturated vapor pressure of ZrCl4 and HfCl4 in KAlCl4 molten salt.

3 Methods to Separate Zirconium & Hafnium

Zirconium and Hafnium Solvent Extraction

This is a method for the separation of zirconium and hafnium using solvent leather. Compared with other separation methods of zirconium and hafnium, this method has the advantages of large production capacity, simple process, and easy to achieve continuously. It is the most important method for the separation of zirconium and hafnium.

The reagents used in this method mainly include ketone extractant, neutral phosphorus-containing extractant and amine extractant. There are three extraction processes of MIBK, TBP and N235. There are two main types of extraction equipment, one is the extraction tower, and the other is the box-type mixer-settler. The former is used by the MIBK process, and the latter is used by TBP and N235 extraction process. The extraction tower occupies a small area and has a large production capacity. The box-type mixer-clarifier is simple in structure and stable in operation, and is generally made of acid-resistant materials such as plastic or plexiglass.

Further Reading: Separation of Zirconium and Hafnium by Solvent Extraction

Zirconium and Hafnium Ion Exchange Separation

As the name suggests, this is a method for the separation of zirconium and hafnium by ion exchange. The production volume of this method is small. Only the former Soviet Union has used it to further separate zirconium and hafnium from the hafnium-rich material separated by the zirconium-hafnium recrystallization method to obtain hafnium oxide, which is used as the raw material for the production of atomic-level sponge hafnium.

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2 Methods of Refining Zirconium

Zone melting and purification

This method does not use crucibles, so it can largely protect the product from contamination by the crucible.

The process of zirconium zone smelting and purification generally includes three stages: raw material preparation, zone smelting and product quality inspection.

Stage 1 Prepare raw materials

The sponge zirconium or zirconium iodide is made into rods by electron beam melting, extrusion, machining and other steps.

Stage 2 Zone smelting

Fix the zirconium rod vertically in the vacuum chamber, use the high-frequency induction coil (or electron gun) as the heat source to melt one end of the rod into a melting zone, and then slowly move the melting zone from one end to the other.

Zirconium is a high melting point metal with strong chemical activity. The vapor pressure at its melting point of 2125K is low, and zone smelting is easier to carry out at this time.

The main factors affecting this stage are the purity of raw materials, vacuum pressure, zone melting speed and zone melting times.

Schematic-representation-of-the-zone-melting-process-with-single-heater
Schematic representation of the zone melting process with single heater. Curtolo, Danilo & Friedrich, Semiramis & Friedrich, Bernd. (2017). High Purity Germanium, a Review on Principle Theories and Technical Production Methodologies. Journal of Crystallization Process and Technology. 07. 65-84. 10.4236/jcpt.2017.74005.

Stage 3 Inspect Product Quality

The head and tail sections of the zirconium rod obtained in the previous stage were excised for sampling. Its various parameters are measured by mass spectrometry, hardness determination or specific resistance.

E-beam melting and purification

Zirconium has a great affinity for oxygen and nitrogen, and 0.2% nitrogen or oxygen in zirconium becomes brittle, making it difficult to process into materials. In this method, the metal to be purified is bombarded with electrons in a vacuum to melt it. In the purification process, in addition to avoiding the oxidation and nitridation of zirconium, the gas dissolved in the zirconium can also escape, the mixed oxide can be decomposed or evaporated, and metal impurities (such as copper, aluminum, gold, iron, manganese, chromium, etc.). The processing properties, electrical properties, magnetic properties and mechanical properties of the zirconium ingot purified by electron beam smelting are obviously better than the raw zirconium.

Scheme of Electron beam melting and refining (EBMR) process
Scheme of Electron beam melting and refining (EBMR) process. Vutova, Katia & Donchev, Veliko. (2013). Electron Beam Melting and Refining of Metals: Computational Modeling and Optimization. Materials. 6. 4626-4640. 10.3390/ma6104626.

An electron beam melting furnace is composed of an electron gun system, furnace body, vacuum system, raw material adding system, mold mechanical device, operation control system, and high voltage power supply device. The larger the scale is, the lower the product smelting cost is. At present, the smelting process is developing into a semi-continuous or continuous production mode to improve production efficiency and production capacity.

The quality of zirconium ingot purified by electron beam melting depends on the raw material, the melting speed, and the power of the melting furnace.

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3 Types of Zirconium Based Getter Materials

Zirconium-based getter material refers to the alloy with high absorption active gas characteristics formed by adding other elements based on zirconium.

Before sealing in vacuum tubes and devices, the material must be heated and activated under vacuum conditions for fast and effective gettering. The function of activation is to remove the passivation film formed on the surface during the manufacturing and storage process to expose the fresh surface, which is conducive to the overall gettering, so as to achieve the purpose of absorbing a large amount of oxygen, nitrogen, hydrogen, carbon monoxide, carbon dioxide, hydrocarbons, and water vapor.

Zirconium-aluminum alloy, zirconium-graphite, and zirconium-vanadium-iron alloy are widely used zirconium-based getter materials today.

Zirconium-aluminum alloy getter

Zirconium-aluminum alloy getter can be made into ring-shaped material and composite strip-shaped material.

(1) Ring-shaped material. The material has poor gettering performance at room temperature and is usually not used for gettering at room temperature. This material is commonly used in electronic tubes, various vacuum devices, special lamps, inert gas purification, zirconium-aluminum getter pumps, etc.

(2) Composite strip material. The advantage is that the amount of mercury can be accurately controlled, and it does not decompose or generate mercury vapor below 500°C, thereby greatly reducing environmental pollution, preventing workers from mercury poisoning, and improving lamp quality and life. It has been widely used in fluorescent lamps and energy-saving lamps.

ZR1422 Zirconium Aluminum Alloy, ZrAl Alloy
ZR1422 Zirconium Aluminum Alloy, ZrAl Alloy

Zirconium graphite getter

Zirconium graphite getter is often used in high-reliability and long-life vacuum tubes and devices for long-term operation and storage, such as traveling wave tubes, X-ray tubes, trigger tubes, ceramic tubes, and laser tubes.

Zirconium-vanadium-iron alloy getter

Zirconium-vanadium-iron alloy getter is a low-temperature activated getter material composed of zirconium, vanadium, and a small amount of iron. It is divided into two types:

(1) Zirconium vanadium ferroalloy getter material, smelted by 70%zr+24.6%V+5.4%Fe in electric arc furnace or medium frequency induction furnace under vacuum or filled with inert gas, then crushed, pulverized, and then pressed into getter elements.

(2) (Zirconium vanadium ferro)/zirconium getter material. It is made by adding the zirconium vanadium ferroalloy powder prepared in (1), adding zirconium powder in a certain proportion, mixing evenly, and then pressing, high temperature and high vacuum sintering and other processes. into a suction element. Product forms are powder, flakes, rings, and strips.

These two zirconium-vanadium-iron alloy getters are low-temperature activated getters, and the activation process is as follows: the temperature is 400-600°C, the vacuum degree is 10-2-10-4Pa, and the maintenance is 10-30min. The working temperature is from room temperature to 350℃.

Zirconium-vanadium-iron alloy getter is widely used in stainless steel vacuum insulated cups (bottles), solar vacuum water heaters, high-efficiency oil-insulated pipes, and vacuum tube containers that are only allowed to operate at 500°C.

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Zirconium – A Vacuum Material

Properties of Zirconium

Zirconium easily absorbs hydrogen, nitrogen, and oxygen; zirconium has a strong affinity for oxygen, and oxygen dissolved in zirconium at 1000°C can significantly increase its volume. The surface of zirconium is easy to form an oxide film with luster, so its appearance is similar to that of steel. Zirconium is resistant to corrosion but is soluble in hydrofluoric acid and aqua regia. At high temperatures, zirconium can react with non-metallic elements and many metal elements to form solid solutions. Zirconium has good plasticity and is easy to be processed into plates, wires, etc. Zirconium can absorb a large amount of oxygen, hydrogen, nitrogen, and other gases when heated, and can be used as a hydrogen storage material. The corrosion resistance of zirconium is better than that of titanium, and it is close to niobium and tantalum. Zirconium and hafnium are two metals with similar chemical properties that are symbiotic together and contain radioactive substances.

Applications of Zirconium

Like lithium and titanium, zirconium can strongly absorb nitrogen, hydrogen, oxygen, and other gases. When the temperature exceeds 900 degrees Celsius, zirconium can absorb nitrogen violently; under the condition of 200 degrees Celsius, 100 grams of metal zirconium can absorb 817 liters of hydrogen, which is equivalent to more than 800,000 times that of iron. This characteristic of zirconium makes it widely used in the electric vacuum industry. People use zirconium powder to coat the surface of the anode and other heated parts of electric vacuum components and instruments to absorb residual gas in vacuum tubes. The high vacuum tubes and other electric vacuum instruments made in this way have high quality and long service life.

high vacuum tubes

Zirconium has a small thermal neutron capture cross-section and has outstanding nuclear properties, so it is an indispensable material for the development of the atomic energy industry and can be used as a reactor core structural material. Zirconium powder is easy to burn in the air and can be used as a detonator and smokeless powder. Zirconium can be used as an additive for deoxidation and desulfurization of high-quality steel and is also a component of armor steel, cannon steel, stainless steel, and heat-resistant steel.

Zirconium can also be used as a “vitamin” in the metallurgical industry to exert its powerful deoxidation, nitrogen removal, and sulfur removal effects. Adding 1/1000 zirconium to steel will increase the hardness and strength amazingly; zirconium-containing armored steel, stainless steel, and heat-resistant steel are important materials for the manufacture of defense weapons such as armored vehicles, tanks, cannons, and bulletproof panels. When zirconium is mixed into copper and drawn into copper wire, the conductivity is not weakened, while the melting point is greatly improved, which is very suitable for high-voltage wires. Zirconium-containing zinc-magnesium alloy is light and resistant to high temperatures, and its strength is twice that of ordinary magnesium alloys. It can be used in the manufacture of jet engine components.

Zirconium powder is characterized by a low ignition point and fast burning speed and can be used as a primer for detonating detonators, which can explode even underwater. Zirconium powder plus oxidant is like adding fuel to the fire, it burns with strong light and dazzling, and it is a good material for making tracer and flare.

Zirconium alloys and their applications

Zirconium alloy is a non-ferrous alloy composed of zirconium as the matrix and other elements are added. The main alloying elements are tin, niobium, iron, and so on. Zirconium alloy has good corrosion resistance, moderate mechanical properties, low atomic thermal neutron absorption cross-section in high temperature and high-pressure water and steam at 300-400 °C, and has good compatibility with nuclear fuel. In addition, zirconium alloy has excellent corrosion resistance to various acids, alkalis, and salts, and has a strong affinity with oxygen, nitrogen, and other gases, so it is also used in the manufacture of corrosion-resistant parts and pharmaceutical machinery parts. For example, it is widely used as a non-evaporable getter in the electric vacuum and light bulb industries.

zirconium alloy

There are two types of zirconium alloys produced on an industrial scale: the zirconium-tin series and the zirconium-niobium series. The former alloy grades are Zr-2 and Zr-4, and the typical representative of the latter is Zr-2.5Nb. In zirconium-tin alloys, the alloying elements tin, iron, chromium, and nickel can improve the strength, corrosion resistance, and thermal conductivity of the corrosion-resistant film, and reduce the sensitivity of the surface state to corrosion. Usually, Zr-2 alloys are used in boiling water reactors, and Zr-4 alloys are used in pressurized water reactors. In zirconium-niobium-based alloys, the corrosion resistance of the alloy is the best when the addition amount of niobium reaches the solid solution limit of the crystal structure of zirconium at the service temperature. Zirconium alloy has isomorphous transformation, the crystal structure is body-centered cubic at high temperature, and hexagonal close-packed at low temperature. Zirconium alloy has good plasticity and can be made into pipes, plates, bars and wires by plastic processing; its weldability is also good and can be used for welding.

Other Zirconium Compounds

Zirconium dioxide and zircon are the most valuable compounds in refractory materials. Zirconium dioxide is the main material of new ceramics and cannot be used as a heating material that resists high-temperature oxidation. Zirconium dioxide can be used as an additive for acid-resistant enamel and glass, which can significantly improve the elasticity, chemical stability, and heat resistance of glass. Zircon has a strong light reflection performance and good thermal stability and can be used as sunscreen in ceramics and glass. Zirconium can absorb a large amount of oxygen, hydrogen, ammonia, and other gases when heated, and is an ideal getter. For example, zirconium powder is used as a degassing agent in electronic tubes, and zirconium wire and zirconium sheets are used as grid supports and anode supports.

Powdered iron mixed with zirconium nitrate can be used as glitter powder. Zirconium metal is used almost exclusively as the cladding for uranium fuel elements in nuclear reactors. It is also used to make photographic flashes, as well as corrosion-resistant containers and pipes, especially hydrochloric and sulfuric acids. Zirconium chemicals can be used as crosslinking agents for polymers.

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Applications of Zirconium Silicate Grinding Media

Zirconium Silicate is a high-quality and inexpensive opacifier with a high refractive index of 1.93-2.01 and chemical stability. It is widely used in the production of various ceramics. Besides, Zirconium Silicate has a high melting point, so it is also widely used in refractory materials, zirconium ramming materials for glass furnaces, casting materials, and spray coatings.

The zirconium silicate media ball is one of its kind, offering users the highest quality and superior grinding levels with improved abrasion resistance, better cost-effectiveness and lower overall contamination rates. Zirconium silicate beads are formulated in strict quality-controlled laboratory containers, in which they undergo specialized instillation techniques, followed by high-temperature sintering and final surface treatment. Compared to other alternative grinding media options such as glass beads or alumina, this ultra-hard media is an ideal solution for grinding special and complex products.

Zirconium Silicate Grinding Media
Zirconium Silicate Grinding Media

The basic characteristics of a good quality zirconium silicate grinding media are that they are high in density, shiny and smooth in appearance, and consist of a uniform solid spherical shape which in turn assures better efficiencies, decreased media wear, and a much longer life span respectively. Additional specialized techniques such as solidifying the media from surface to center result in further strengthening of the molecular structure of ZrSi beads. Zirconium silicate media balls exist in varying sizes and diameters in accordance with each buyer’s prerequisites.

ZrSi04 applications and uses are tremendous and widespread from everyday products such as paints and inks to ceramics, pharmaceuticals, and even in controlled quantities within edible food materials. Zirconium Silicate grinding media plays an integral role as an emulsion agent in order to achieve a ceramic glaze in refractory’s and on cutlery etc. Also being chemically inert and nonreactive allows ZiSi04 media to be used for grinding plastic on a mass level and at economical costs. Moreover, zirconium casting refractories of all kinds utilize this media for operational purposes within glass melting furnaces, cement production and heat/fire resistant porcelain among many others. On a generalized level, Zirconium Silicate grinding media performs numerous operations including mold cleaning of stainless steel, plastic as well as nonferrous materials, mechanical polishing, buffing and eventual after-cleaning processing.

On an overall rating scale, the benefits of this industrial product being extremely dense and strong results in creating an ideal surface roughness and metallic depth with a much lower breakage or contamination rate comparatively. These attributes in turn render Zirconium Silicate milling balls suitable for application on all types of materials and within both wet and dry environments easily.

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Two Surface Treatment Technologies for Zirconium Materials

The surface of the zirconium rod and zirconium alloy must be clean and smooth before joining, heat treatment, electroplating and forming. This article introduces 2 types of surface treatment methods for zirconium materials.

  1. Surface decontamination

Grease, oil, and lubricants produced during zirconium machining or other processing can be removed in a number of ways. Commonly used cleaning methods are

1) cleaning with alkaline or milky detergent in a soaking tank;

2) cleaning with ultrasonic vibration;

3) rinsing with acetone or trichloroethylene or steam degreasing and

4) cleaning with other cleaning agents.

Small stains can also be removed by hand wiping with some solvents such as acetone, alcohol, trichloroethylene, or a trichloroethylene substitute. In the electrolyte system, if the voltage and current can be controlled to avoid anodic polarization or spark discharge and pitting, positive or negative polarity decontamination can be used. Before heat treatment and bonding, the surface of the zirconium material must be cleaned to prevent metal contamination and the resulting deterioration of ductility.

Surface Treatment Technologies for Zirconium Materials

  1. Blast cleaning

Mechanical decontamination methods such as sandblasting, shot blasting, and evaporative cleaning can remove dirt and lubricants from zirconium and hafnium surfaces. Alumina, silicon carbide, silica and steel grit are ideal media for mechanical decontamination. The decontamination medium used should be replaced regularly to avoid increased workload due to particle passivation.

Grinding or shot peening may cause residual compressive stress and thermal deformation on the surface of the material, especially the surface of the sheet. Hot deformation may also occur during subsequent rolling and profile machining.

Blast cleaning is not a substitute for pickling. Blast cleaning cannot remove surfaces contaminated with interstitial elements such as carbon, oxygen, and nitrogen. In general, blast cleaning followed by pickling can ensure the complete removal of surface contamination and cold-worked layers, resulting in a smooth, shiny metal surface.

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Application of Zirconium Silicate in Ceramic Industry

Introduction of Zirconium Silicate

Zirconium silicate is a non-toxic, odorless white powder. It is usually made of natural high-purity zircon sand concentrate, which needs to be processed by ultra-fine grinding, iron removal, titanium processing, surface modification treatment and other processes. Zirconium silicate powder is a high-quality and inexpensive ceramic glaze opacifier, brightener, anti-seepage agent and stabilizer.

Main roles of Zirconium Silicate

  1. Improve the hardness of ceramic glaze

Zirconium silicate has good chemical stability, and can significantly improve the separation performance of ceramic glaze and improve the hardness of ceramic glaze;

  1. Whitening effect

Zirconium silicate powder can whiten ceramic glazes.

Application of zirconium silicate in the traditional ceramic industry

Zirconium silicate is mainly used for high-temperature opaque glaze in daily ceramics and sanitary ware.

Application of zirconium silicate

Many companies add a small amount of zirconium silicate or zircon powder to polished tiles and glazed products to increase stability.

Another function of zirconium silicate in the traditional ceramic glaze is to increase the hardness of the ceramic glaze and improve its wear resistance of the glaze. Zirconium silicate is generally used in raw glazes with little or no zircon powder. Compared with zircon powder, zirconium silicate powder is finer and brighter.

Engobe generally uses zirconium silicate, which can increase the whiteness of the engobe and adjust its expansion coefficient and stability.

Zirconium silicate has a good effect when added to the medium and high-temperature glaze of raw materials. A certain amount of zirconium silicate is generally added to the high-gloss and matt glazes of sanitary ware and glazed porcelain tiles.

Conclusion

Zirconium silicate is a high-quality and inexpensive opacifier, which is widely used in various architectural ceramics, sanitary ceramics, daily-use ceramics, and first-class ceramics. Zirconium silicate has also been further used in the production of color picture tubes in the TV industry, emulsified glass in the glass industry, and enamel glaze production. Zirconium silicate is also widely used in refractory materials, glass furnace zirconium ramming materials, castables and spray coatings due to its high melting point.