Sintering Process of Silicon Carbide Tube

The sintering method of the silicon carbide tube mainly includes reaction sintering, pressureless sintering, hot pressing sintering, and hot isostatic pressing.

Reaction sintering is based on the reaction: 3Si(s) + 2N2(g) = Si3N4 (s) The initial temperature of the nitridation reaction is at 1100, and then gradually increases to 1420 ° C. The whole process takes several days, since the reaction is an exothermic reaction. Therefore, the heating rate should be carefully controlled. The resulting product, typically maintained at a temperature below 1400, is a mixture of alpha-, beta-Si3N4 having a porosity of 15% at 15 °C.

The advantage of reaction sintering is that no additional additives are added. Its characteristics are: 1) the strength of the material does not decrease significantly at high temperatures; 2) the size and shape of the product can be changed to produce a complex shape; 3) When welding two parts, simply connect them together for nitrogen Chemical. In reaction sintering, the key factor affecting product quality is to control the reaction temperature. The three-step heating method finally raises the furnace temperature above the melting point of silicon, often referred to as ultra-temperature nitriding.



At present, in addition to reaction sintering, methods for preparing high-density silicon carbide tubes include pressureless sintering, hot pressing sintering, and hot isostatic pressing. The SiC component of complex shape and large size can be prepared by a pressureless sintering process, and thus is considered to be the most promising sintering method of SiC ceramic.

Only a simple shape of the SiC component can be prepared by the hot press sintering process, and the number of products prepared by one hot sintering process is small, which is disadvantageous for commercial production. Although the hot isostatic pressing process can obtain a SiC product of a complicated shape, the green body must be encapsulated, so that industrial production is also difficult to achieve.

The performance of SiC tubes varies depending on the sintering method. In general, the overall performance of pressureless sintered SiC tubes is superior to that of reactive sintered SiC, but inferior to hot pressed sintering and hot isostatically sintered SiC tubes.

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What is the difference between alumina and zirconia ceramic rods?

Ceramic rods are mainly formed by zirconia ceramics or alumina ceramic materials through molding, sintering and processing. Ceramic rods have been widely used in military, aerospace, industrial and other fields and those markets have a large demand for ceramic rods. The demand for ceramic rods varies from industry to industry, and their requirements are different. But the main considerations are the same: wear resistance, thermal insulation and high temperature resistance, corrosion resistance, lubrication.

The main materials of ceramic rods are mainly zirconia ceramics and alumina ceramics. What is the difference between these two types of ceramic rods?

Zirconia ceramic rods:
Zirconia, or Zirconium dioxide (ZrO2), is a white crystalline oxide of zirconium. Its most naturally occurring form is the mineral baddeleyite with a monoclinic crystalline structure. Cubic zirconia is adopant stabilized cubic structured zirconia, and it can be synthesized in various colors for use as a gemstone and a diamond simulant.

The biggest advantage of zirconia ceramic rods is their very good toughness. Zirconium oxide ceramic rods are widely used in the fields of motor shafts, motor shafts, grinding, needle gauges, etc. In particular, ceramic center rods are used in the field of heat dissipation products to replace traditional stainless steel center rods.

Alumina ceramic rods:
Alumina, orAluminium oxide, is a chemical compound of aluminium and oxygen with the chemical formula Al2O3. It is the most commonly occurring of several aluminium oxides, and specifically identified as aluminium(III) oxide. It is commonly called alumina and may also be called aloxide, aloxite, or alundum depending on particular forms or applications.

Alumina ceramic rods can withstand high temperatures up to 1700 degrees, have good conductivity, mechanical strength and high temperature resistance. The density of alumina ceramic rods is relatively low and convenient for transportation. However, alumina ceramic rods have poor toughness and are easy to break and break. Alumina ceramic rods are widely used, and have been soaked in various fields such as electronic appliances and mechanical parts.
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Use of Titanium Coated Film

Titanium thin film is generally used to improve the wear resistance of objects. For example, taps and drill bits for high-speed machining centers can be coated with titanium to improve the wear resistance of the tool, and the surface treatment of the piston ring is also titanium-plated, also in order to improve the wear resistance.
Related: Everything you need to know about titanium sputtering target

The titanium film not only has a very high wear resistance, but also has good decorative and aesthetic properties. The color of the titanium film is golden. After coating with a thin titanium film, the object can prevent oxidation, rust, etc.



Commonly used titanium coating processes
1. Titanium coating processes: vacuum coating and spraying process.
The vacuum coating includes: magnetron sputtering method, arc ion plating method, evaporation method, etc. Titanium sputtering targets are indispensable raw materials in the vacuum coating process.
The method of spraying is cold spraying.
Both coating methods have their own advantages. The advantage of vacuum coating is that the film it coated is very thin, and has high compactness and excellent performance. While the biggest advantage of spraying is that it is cheap. However, the coating is very thick to the order of millimeters and the surface roughness requires subsequent processing.

What kind of gas does the magnetron sputtering titanium need?
1. When a metal film is applied, argon gas is generally used as a working gas. It is an inert gas, and does not undergo oxidation when the substrate is heated under vacuum. Generally speaking, argon gas is used to adjust the pressure of the furnace body, and the effect on color is not obvious!
2. Oxygen is generally used for plating non-metallic films, such as TiO2, and there is no need to worry about membrane oxidation after plating.
3. Nitrogen is the gas that is flushed into the vacuum chamber when the target coating is changed, so that the pressure in the vacuum chamber and the atmospheric pressure are kept equal, and the other film can be plated for the target. Nitrogen generally increases the yellow b value, such as zirconium, which is golden yellow!


What color can the titanium film form through different gases?
1. TiN (gold)
2. TiZrN (Gold)
3. TiC, TiNc (bright gray ~ gun black)
4. TiNC (rose gold ~ brown)
5. TiO (gem blue ~ iridescent)

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六方晶窒化ホウ素および立方晶窒化ホウ素 （Hexagonal Boron Nitride and Cubic Boron Nitride）

In recent years, new materials based on ceramics have developed rapidly. Boron nitride ceramic is a kind of hexagonal crystal system with phosphorus structure and special physicochemical properties. It is a new industrial material developed with the development of the aerospace and electronics industry and has a wide range of applications in industry and production.

At present, research on boron nitride is mainly concentrated on the hexagonal phase (h-BN) and the cubic phase (c-BN). Hexagonal boron nitride has good lubricity, thermal conductivity and high temperature performance. Recent studies have shown that the hexagonal phase is also in thermodynamic equilibrium and steady state at room temperature and pressure. The main application of hexagonal boron nitride is to act as a raw material for the synthesis of cubic boron nitride.



Hexagonal boron nitride is called white graphite because it has a similar layered crystal structure and physical and chemical properties similar to graphite (good lubricity and thermal conductivity). Hexagonal boron nitride is commonly used as a sintered ceramic material. In addition, due to its high thermal conductivity, good electrical insulation properties, low thermal expansion coefficient and non-thermal properties, h-BN structural ceramics have been widely used in high temperature insulation components, atomic energy, metallurgy, aviation and other fields. As a raw material for synthesizing cubic boron nitride, hexagonal boron nitride is a theoretical low-temperature stable phase, and its excellent performance is more attractive. Therefore, hexagonal boron nitride is commonly used to synthesize cubic boron nitride.

Boron nitride ceramics have excellent thermal stability and dielectric properties. They are one of the few compounds that can decompose at high temperatures, and have excellent thermal and electrical stability even over a wide temperature range. However, single-phase boron nitride ceramics have not been put to practical use due to low strength, hardness, elasticity, high thermal conductivity, low corrosion resistance, and difficulty in forming a shape component.
As an advanced ceramic material, boron nitride is widely favored in the field of materials research due to its excellent mechanical properties. The new boron nitride synthesis method has become a hot topic in boron nitride research.

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How will the energy change our future?

Prior to the 1900s, the global population was fairly low and easily managed. There were far less people producing much lower amounts of pollution. Unfortunately, as the world developed new and better technology to reduce suffering and increase standards of living, a side effect appeared. The quality of the environment started to deteriorate, which contributed to global warming and interesting problems such as the Great Pacific Garbage Patch. A new approach to technology was developed to combat these problems; green technology. Green technology serves to either mitigate the damage caused by the use of technology, or reduce pollution through its use. The three fields that will be most important in the next thirty years will be power generation, filtration, and the creation of more efficient systems.

Most people can identify the main forms of renewable energy; there’s solar, hydroelectric, geothermal, wind, and biomass. Unfortunately, only 17.1% of energy generated in the U.S. during 2017 was renewable, primarily from hydropower and wind (EIA). In the future, solar panel technology will most likely become more efficient and cheaper, as it is still a relatively young technology. The United States government currently offers a 30% tax credit for the purchase of solar panels, which should incentivise more people to install the devices. The increased availability and affordability of solar panels alongside innovations making them more efficient should increase the total power generated significantly. This could lead to a surge of solar panels in sunny regions of the world, reducing the need for fossil fuel power generation and minimizing power costs for households.

Biomass is an often forgotten form of green energy, but it is still significant, accounting for 1.6% of U.S. energy produced in 2017 (EIA). Biomass does tend to be less efficient than coal, however it is often used to co-fire in coal plants. This is because biomass burns much cleaner than coal, with little to no sulfur or mercury emissions and essentially being carbon neutral (PSU). The benefits are two-fold; a job market is created for farming the biomass, and the coal factories can reduce emissions. This innovation may not get rid of coal by itself, but it certainly helps maintain the environment while coal is still in use. Biomass should increase the total number of jobs and throttle coal emissions over the next thirty years. If carbon emission restrictions are strengthened, then coal would most likely fall out of favor and be replaced with biomass, as both resources generally use the same setup to produce power.

According to the CDC, approximately 780 million people do not have access to improved water sources. This water tends to be dirty, containing particulate that can harm the body, including deadly diseases such as Guinea Worm. Alongside this problem, about 2.5 billion people do not have access to improved sanitation, leading to more diseases and deaths. A green technology known as filtration could easily solve this problem, and it is already implemented for most of the world. Multiple methods exist, including chemical processes, radiation/heat, and very fine filters to remove the particulate and disease. At this point the problem is more deployment than development, and within the next thirty years filtration systems should be implemented to reach more of the global population, and will help prevent a lot of disease and suffering, particularly in Africa and Asia.

A unique facet of green innovation is making existing technology more efficient. This kind of engineering is present in all fields, in almost every device being created. A large proponent in the U.S. for general efficiency is the EPA, with the Energy Star program. This program focuses on cutting costs and saving energy for businesses and individuals through efficiency, which has the added benefit of helping the environment. Not only does this help reduce power consumption and therefore emissions, but also saves money for businesses and individuals over the course of a lifetime, enabling them to spend money on other things to improve their quality of life.

Environmental technology is a necessary development for the world today. With more efficient products using clean sources of power, less pollution will be generated overall. Effective distribution of filtered water and other basic necessities will enable entire regions of deficient persons to contribute to the global stage. The future for environmental technology is not only bright; it’s green.

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