Tungsten Oxide Ceramic Preparation

Produce nano WO3 ceramic powder preparation by ball mill method. 

A ball mill, a type of grinder, is a cylindrical device used in grinding (or mixing) materials like ores, chemicals, ceramic raw materials and paints. Ball mills rotate around a horizontal axis, partially filled with the material to be ground plus the grinding medium. Different materials are used as media, including ceramic balls, flint pebbles and stainless steel balls. An internal cascading effect reduces the material to a fine powder. Industrial ball mills can operate continuously, fed at one end and discharged at the other end. Large to medium-sized ball mills are mechanically rotated on their axis, but small ones normally consist of a cylindrical capped container that sits on two drive shafts (pulleys and belts are used to transmit rotary motion). A rock tumbler functions on the same principle. Ball mills are also used in pyrotechnics and the manufacture of black powder, but cannot be used in the preparation of some pyrotechnic mixtures such as flash powder because of their sensitivity to impact. High-quality ball mills are potentially expensive and can grind mixture particles to as small as 5 nm, enormously increasing surface area and reaction rates. The grinding works on the principle of critical speed. The critical speed can be understood as that speed after which the steel balls (which are responsible for the grinding of particles) start rotating along the direction of the cylindrical device; thus causing no further grinding.

The main factors that affect the efficiency of the ball mill are: 

(1) ball mill speed. Ball mill speed directly affects the state of motion in the barrel, ball mill attached to the cylinder wall if over-speed, losing crushing effect; if the speed is too slow, that is much lower than the critical speed, ball mill barrel rise a little then came down, crushing effect is little; when the speed is appropriate, ball is close to the tube wall, after some distance, ball falls away from the tube wall to give powder the greatest impact and abrasive action, with the highest crushing efficiency. 

(2) ball. The more ball was added during ball milling, the higher crushing efficiency, but too much balls will occupy the available space, resulting in lower overall efficiency. 

(3) addition amount of water and electrolytes. 

(4) loading. 

The WO3 powder directly weighed, adding some deionized water and wet grinding carbide ball in a plastic drum, dried and sieved to obtain a powder-like nano.

Tungsten Oxide Ceramic

Tungsten trioxide (WO3) is an extremely important high-tech materials, this material is non-linear, high-dielectric constant, electrochromic, with gas detection, chemical catalysis and other features. For the features of WO3, the nano-powder of WO3 can be fired into varistor ceramics, ceramic capacitors, light (electricity) color ceramic film, gas-sensing ceramics, photocatalytic degradation ceramic membrane, battery electrode ceramic materials, microwave absorbing ceramic film, new high-temperature thermoelectric ceramics and functional ceramics and ceramic films, which has great potential in many chemical, energy, electricity and other fields.

There are two preparation methods of ceramic raw materials, that mechanical disruption and synthesis. The former one uses mechanical principle crushing coarse particles to obtain fine powder, which has the advantages of large amount of production and low cost, but there are problems of impurities mixed in the crushing process, and it is difficult to obtain submicron particle size. And the powder produced by synthesis has high purity, small particle size, component uniformity, suitable for high performance requirements, low production needs of advanced ceramic materials.

Nanometer WO3 powders prepared by mechanical milling as a raw material of sintering tungsten trioxide ceramics, the systematic study of influence of milling parameters on particle size, the grinding can achieve the best results.

AMT/SiO2 Catalyst on Orthortho-Hydroxy Anisole Production II

Ammonium metatungstate, also known as AMT, is a tungsten chemical in the form of highly soluble hydrated crystals. Global Tungsten & Powders AMT is produced as minus 10-mesh powder to meet stringent demands in the catalyst, medical, semiconductor and other high-technology industries. GTP AMT is also used in materials research and in analytical chemistry. At room temperature, aqueous solutions can be saturated up to 70% by weight of contained WO3. This equates to 1.6 kilograms per liter or 13.3 pounds per gallon.

AMT / SiO2 catalyst calcined at different temperatures has different degrees of AMT decomposition, resulting in different properties of the catalyst surface pH center, resulting in catalyst performance vary. The activity and stability of catalyst prepared at low firing temperature calcination is much better than a catalyst prepared at high firing temperature. Weak acid-weak alkali centers on the catalyst surface is the main activity center of catechol and methanol monoetherification reaction to produce ortho-hydroxy anisoles. the main reason for the reduced activity is coke on the catalyst surface during the reaction. the catalyst after inactivation was calcined at a higher temperature and regeneration treatment then the reactivity partially restored, but still significantly lower than the fresh catalyst, and the stability of the catalyst after regeneration process is poor. This may be the high temperature regeneration properties of the active center of the catalyst surface (including pH properties) has changed, so that the regenerated catalyst is more easily inactivated.

AMT/SiO2 Catalyst on Orthortho-Hydroxy Anisole Production I

Orthortho-hydroxy anisole is important fine chemical intermediates and chemical raw materials, with a wide range of applications. Pyrocatechol - Methanol Gas phase single etherification method to produce orthortho-hydroxy anisole has attracted much attention due to its advantages of economic and environmental, some effective catalyst systems of this reaction have been found including a variety of complex oxides, phosphates and zeolite.

According to preliminary studies on phosphates and phosphate multicomponent catalyst, it’s found that a weak acid - weak alkali catalyst usually shows high activity and selectivity on the reaction of pyrocatechol and methanol vapor phase synthesis of orthortho-hydroxy anisole. Recently, scholars have found that supported ammonium metatungstate (AMT) catalyst prepared by SiO2, TiO2, and Al2O3 as the carrier has good catalytic performance on this reaction. In which the tungsten loading of 7.9% of AMT / SiO2 catalyst has the best performance. Preliminary characterization results show that the weak acid - weak alkali species formed by ammonium metatungstate partial decomposition are the the active center of the catalytic reaction in roasting preparation processing. On this basis, the study focused on the influence of calcination temperature on pyrocatechol and methanol vapor single etherification performance with AMT / SiO2 catalyst and examine the stability and performance of the catalyst regeneration. Meanwhile, according to X-ray diffraction (XDR), infrared spectroscopy (IR), temperature programmed desorption (TPD), scanning electron microscopy (SEM) and differential thermal - thermogravimetric (TG-DTA), catalyst structure, surface acidity the nature and reasons for deactivation were discussed.

Morphology and Size of Ammonium Metatungstate Microsphere Prepared by Spray Drying Method

Ammonium metatungstate (AMT) is usually used as one of the precursors of tungsten carbide (WC) catalyst, and the properties of AMT precursor affect the morphology and size distribution of WC microsphere, which have a finally effect on the catalyst activity.

In this work, the mechanisms of airflow and centrifugal spray drying methods were introduced, then the AMT microspheres having different morphologies were prepared by using these two kinds of spray drying methods, and the morphology and size of the microspheres prepared were studied. The results show that the morphology of the powder prepared by centrifugal spray drying is solid sphere, and it is different from that of the powder prepared by airflow spray drying, which is hollow sphere. For the airflow spray drying method used, the effects of solution concentration, feed rate and surfactant on the particle size of products were investigated.

It was found that the solution concentration is the most important factor affecting the particle size, and under different drying conditions, the minimum median diameter (d50) of the dry products is 2.26 μm. This study might provide a referential foundation for the morphology and size control of hollow global WC microspheres prepared by the gas-solid reaction method of spray drying sphere miniaturization.

Ammonium Metatungstate(AMT) Industry China Market Research Report 2016

The China Ammonium Metatungstate(AMT) Industry 2016 Market Research Report is a professional and in-depth study on the current state of the Ammonium Metatungstate(AMT) industry.

The report provides a basic overview of the industry including definitions, classifications, applications and industry chain structure. The Ammonium Metatungstate(AMT) market analysis is provided for the China markets including development trends, competitive landscape analysis, and key regions development status.

Development policies and plans are discussed as well as manufacturing processes and Bill of Materials cost structures are also analyzed. This report also states import/export consumption, supply and demand Figures, cost, price, revenue and gross margins.

The report focuses on China major leading industry players providing information such as company profiles, product picture and specification, capacity, production, price, cost, revenue and contact information. Upstream raw materials and equipment and downstream demand analysis is also carried out. The Ammonium Metatungstate(AMT) industry development trends and marketing channels are analyzed. Finally the feasibility of new investment projects are assessed and overall research conclusions offered.

With 148 tables and figures the report provides key statistics on the state of the industry and is a valuable source of guidance and direction for companies and individuals interested in the market.

Structure and Thermal Decomposition of Ammonium Metatungstate

Ammonium metatungstate, also known as AMT, is a tungsten chemical in the form of highly soluble hydrated crystals. Global Tungsten & Powders AMT is produced as minus 10-mesh powder to meet stringent demands in the catalyst, medical, semiconductor and other high-technology industries. GTP AMT is also used in materials research and in analytical chemistry. At room temperature, aqueous solutions can be saturated up to 70% by weight of contained WO3. This equates to 1.6 kilograms per liter or 13.3 pounds per gallon.

The structure and morphology of ammonium metatungstate (AMT), (NH4)6[H2W12O40]⋅4H2O, and its thermal decomposition in air and nitrogen atmospheres were investigated by SEM, FTIR, XRD, and TG/DTA-MS. The cell parameters of the AMT sample were determined and refined with a full profile fit. The thermal decomposition of AMT involved several steps in inert atmosphere: (i) release of crystal water between 25 and 200 °C resulting in dehydrated AMT, (ii) formation of an amorphous phase between 200 and 380 °C, (iii) from which hexagonal WO3 formed between 380 and 500 °C, and (iv) which then transformed into the more stable m-WO3 between 500 and 600 °C. As a difference in air, the as-formed NH3 ignited with an exothermic heat effect, and nitrous oxides formed as combustion products. The thermal behavior of AMT was similar to ammonium paratungstate (APT), (NH4)10[H2W12O42]⋅4H2O, the only main difference being the lack of dry NH3 evolution between 170 and 240 °C in the case of AMT.