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Two common materials for ceramic toughening (silicon carbide whiskers and nano zirconia)

As new materials in the technological revolution, ceramic materials have attracted the attention of some developed countries as early as ten years ago. The fatal shortcomings of ceramic materials are its brittleness, low reliability and low repeatability, which seriously affect the application range of ceramic materials. Only by improving the fracture toughness of ceramics and providing its reliability and service life can ceramic materials truly become a new type of widely used material. Therefore, ceramic strengthening and toughening technology has always been a hot topic of discussion in the market.

Two commonly used ceramic toughening methods and materials include:

1) Beta Silicon Carbide Whisker(SiC-W) and Particle(SiC) Toughening

Silicon carbide(SiC) whiskers are added to the ceramic materials to improve the brittleness, enhance the toughness and strength of them, so that the ceramic matrix composite material can significantly improve the impact toughness and shock resistance, and reduce the brittleness of the ceramic material. At the same time, the ceramic has protective fibers. So that it will not be oxidized at high temperature, has high temperature strength and elastic modulus.

Ceramic silicon carbide whiskers are small ceramic single crystals with a certain aspect ratio and few defects, so they have high strength and are ideal toughening reinforcements for ceramic matrix composites. The macroscopic morphology of ceramic silicon carbide whiskers is flocculent powder. When preparing composite materials, the whiskers can be directly dispersed and then mixed with the matrix powder uniformly. The mixed powders are also hot-pressed and sintered to obtain dense whisker-toughened ceramic matrix composites.

2) Phase transformation toughening of ZrO2 Zirconia Nanopowder
The phase transformation toughening effect is remarkable, and it is mainly used in zirconia ceramics. Yttrium nano-zirconia(YSZ), phase-transformation toughened ZrO2 feldspar ceramics is a promising new type of structural ceramics. It mainly uses ZrO2 phase-transformation properties to improve the fracture toughness and flexural strength of ceramic materials, so that they have excellent mechanical properties, low high thermal conductivity and good thermal shock resistance. It can also be used to significantly improve the toughness and strength of brittle materials, and is an important toughening agent in composite materials and composite ceramics.

The outstanding properties of ZrO2 ceramics make it one of the most widely used oxide ceramics. Toughened ceramics based on ZrO2 materials have broad application prospects in machinery, electronics, petroleum, chemical industry, aerospace, textile, precision measuring instruments, precision machine tools, bioengineering and medical equipment and other industries. Because the partially stabilized zirconia has low thermal conductivity, good strength and toughness, low elastic modulus, thermal shock resistance and high working temperature (1100 ℃), it is used to manufacture diesel engine parts and internal combustion engine parts. It has the advantages of small size, light weight and high thermal efficiency, and is an effective energy-saving engine. The application of ZrO2 toughened ceramics in internal combustion engines is successful.

If you’re interested in further info or in need of SiC whisker, SiC particles, ZrO2 nanopowders, pls feel free to contact us now!

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3 Types Of Nano Materials Used In Absorbing Materials

The so-called absorbing materials refer to a class of materials that can absorb or greatly weaken the electromagnetic wave energy received by its surface, thereby reducing the interference of electromagnetic waves.

In engineering applications, they require the absorbing material to have a high absorption rate of electromagnetic waves in a wide frequency band, they also require to have light weight, temperature resistance, moisture resistance, corrosion resistance and other properties.

Three commonly used nano materials for absorbing materials are as follows:
1. Carbon series nano materials: nano graphene, carbon nanotubes, etc.

Carbon nanotubes(CNTs) show excellent absorbing properties, and at the same time have the characteristics of light weight, good compatibility, and wide absorbing frequency band. They are the most potential absorbing materials of the new generation.

2. Iron series nanomaterials: nano iron(Fe) powder, nano iron oxide, etc.
Nano metals and alloys are mainly used as wave absorbers in a multi-phase composite way, mostly Fe, Co, Ni and other nano metals and alloy powders, and their wave-absorbing properties are better than single-phase nano metal powders.

3. Ceramic series nanomaterials. Such as silicon carbide whiskers, nano silicon carbide particles, nano silicon nitride, and so on.
Silicon carbide(SiC) has been studied a lot as an absorbent. Silicon carbide not only has certain wave absorbing properties, but also can weaken the infrared signal of the engine, and has the advantages of high temperature resistance, low relative density, good toughness, high strength and high resistivity. SiC is one of the rapidly developing absorbents abroad. The absorption band of nano silicon carbide is wider, and it has a good absorption effect on the millimeter and centimeter bands.

In the increasingly important stealth and electromagnetic compatibility (EMC) technology, the role and status of electromagnetic wave absorbing materials are very prominent. So far, nano-wave absorbing materials mainly work in two aspects: civil and military.

In civilian use, nano-wave absorbing materials are mainly used in human body protection. Due to the application of high-power radar, communication machine, microwave heating and other equipment, preventing electromagnetic radiation or leakage and protecting the health of operators is a new and complex topic, and absorbing materials can achieve this purpose. In addition, today’s household appliances generally have electromagnetic radiation problems, which can also be effectively suppressed by rational use of absorbing materials and their components. .

In the military, it is mainly used in radar shadow technology. Coating absorbing materials on various weapons equipment and military facilities such as aircraft, missiles, tanks, ships, warehouses, etc. can absorb reconnaissance radio waves and attenuate reflected signals, thereby breaking through the defense area of enemy radar. This is a kind of anti-radar reconnaissance, a powerful means of reducing the exposure of weapon systems to infrared-guided missiles and laser weapons.

Nano absorbing materials have the characteristics of light weight, wide frequency bandwidth and good performance, and have a wide range of applications. In the case of the same material, nano size materials are obviously better and can meet the requirements of the development of the times for absorbing materials. It is foreseeable that nano absorbing materials will play a huge role in thermal insulation and energy saving, environmental protection, human protection, and military stealth technology in the future.

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Nano Silver Powder For Antibacterial Fiber and Fabric phoebe

Fiber can adsorb many microorganisms, such as bacteria, viruses, etc. Most of these microorganisms will multiply very quickly at a suitable temperature, and cause various harm to humans. That is, the normal flora is a conditional pathogenic flora. When the body’s resistance decreases, the harmless normal flora may be transformed into a harmful pathogenic flora. Therefore, adding antibacterial agents to fibers has become a demand for people to pursue a high-quality life. The silver-loaded antibacterial polyester fiber and its textiles have good antibacterial properties against Escherichia coli, Staphylococcus aureus, Candida albicans, MRSA, etc. The antibacterial textile produced by the antibacterial fiber is an effective external barrier lower than that of pathogenic microorganisms invading the human body.

The preparation methods of nano-silver antibacterial textiles mainly include fiber modification method and fabric finishing method. The fiber modification method first adds a suitable antibacterial filler to the fiber-forming polymer, and then performs wet or melt spinning, and then processes it into an antibacterial fabric; the finishing of the fabric is by coating or impregnating an antibacterial agent on the surface of the fabric The way to form an antibacterial layer on the surface of the textile material. Each method has its own advantages and disadvantages, and corresponding processing methods can be used in production according to different needs. At present, the production of antibacterial textiles is mainly based on fiber modification. In this method, the ultrafine nano silver powder of  antibacterial agent is used as an additive for spinning. At this time, the antibacterial agent enters the inside of the fiber, so the washing resistance is good and the antibacterial effect lasts for a long time. Experiments show that spherical nano-silver has a good antibacterial effect. The smaller the size of nano-silver particles, the antibacterial ability of the fabric will be improved. The antibacterial performance of nano silver antibacterial fiber remains unchanged after 50 standard washings. During the processing, the added antibacterial agent must have good compatibility and dispersibility with the fiber body. At the same time, the antibacterial agent particles are small and the particle size distribution range is narrow, which cannot affect the spinning; the addition of additives cannot affect the physical properties of the fiber. Performance, including fiber strength and elongation.

According to the antibacterial performance testing standards established by our country, the colony counting method is usually used for antibacterial testing of textiles. This is a quantitative antibacterial testing method. It can not only observe whether the textiles have antibacterial performance, but also obtain specific antibacterial rate values. At present, the antibacterial performance evaluation methods commonly used in the world include: minimum inhibitory concentration (dilute inorganic antibacterial agents into different concentrations for colonies to quantitatively determine the minimum inhibitory concentration of antibacterial agents against bacteria), minimum sterilization concentration (to determine The lowest concentration method to kill bacteria in a certain period of time), agar diffusion method (a qualitative or preliminary method to determine the antibacterial effect of antibacterial agents) and immersion culture method (a quantitative test of the antibacterial effect of antibacterial textiles) ).

Hongwu produces and supplies nano-silver particles and nano-silver dispersions, which can be customized according to customer requirements. Hongwu Nano has always adhered to market-oriented and technology-driven, and it is its responsibility to meet the reasonable demands of customers. Focus on the industry, deep cultivation and meticulous cultivation. Welcome to cooperate. https://www.hwnanomaterial.com.

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The Application of Nano Diamond Powder in Sterilization phoebe

At present, the application fields of nano-diamond power are mainly in aerospace manufacturing, precision machinery, optical instruments, automobile manufacturing and other industries. Specifically:

1. The most ideal polishing agent, can obtain atomic-level polished surface. Especially used for the finishing and polishing of various hard materials such as fine ceramics, integrated circuit chips, various gems, ferrite heads, quartz plates, super-hard alloys, optical lenses, etc.;
2. High hardness and high wear resistance plating and non-plating layer;
3. Metal composite material with high hardness and high wear resistance;
4. Low friction, low wear, high load, long life lubrication system (such as lubrication of various cylinders) and super lubricating oil.
5. PTFE-based composite material with high wear resistance and good lubricity;
6. It is an irreplaceable material for the production of polycrystalline diamond and diamond film.

However, a recent report from the University of Bremen in Germany reported that an international team of researchers from the school found that nanodiamonds can kill bacteria as effectively as metallic silver and copper. Nanodiamonds have a diameter of about 5 nanometers (1 nanometer is equal to 1 billionth of a meter), which is about one-two percent of bacteria, and can be produced by exploding carbon-containing compounds in a high-pressure container. After this gray-brown diamond powder undergoes different heat treatments, different chemical groups will be formed on the surface. Researchers have discovered that some nanodiamonds have strong bactericidal properties and can kill bacteria in a short time. A specific oxygen-containing group called acid anhydride on the surface of nanodiamonds seems to be the reason for their bactericidal properties. The researchers said that experiments have shown that nano diamond particles with bactericidal properties may be used to produce surface coatings, bactericides, and so on.

The research results were published in the professional journal “ACS Nano”. Researcher Yulia Waring believes that when many bacteria are resistant to antibiotics, the discovery of a new type of antibacterial material can be described as a “breakthrough”, which is expected to spawn a new diamond application market, Hongwu Nano Getting involved in the production of nanodiamonds is also looking forward to the wide application of nanodiamonds in antibacterial aspects.

Hongwu nano diamond ash powder can produce particles with a diameter of <10nm with a purity of more than 99%. If you need more product information, please feel free to contact us.

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Nano tin bismuth(Sn-Bi) alloy —fusible alloy/low melting point alloy/environmentally friendly alloy

Nano tin bismuth alloy is a low-melting-point and environment-friendly alloy. Low-melting-point alloy refers to a fusible alloy with a melting point lower than 232°C (the melting point of Sn), usually composed of low-melting-point metal elements such as Bi, Sn, Pb, and Cd.

 

Fusible alloys have good fluidity after heating and melting, so this type of low melting point metal is also widely used in casting methods. The superiority is obvious. In addition, low melting point metals are also widely used in medicine to make blocks for radiotherapy. Blocks made of fusible alloys can effectively block normal human tissue during radiotherapy. The method of making blocks with low melting point metal nanoparticles alloys effectively improves the accuracy and safety of radiation therapy.

 

Low melting point alloys are often widely used as solders, as well as heat-sensitive components such as fusible cutouts and fuses in electrical appliances, steam, fire protection, fire alarms and other devices.

Specific application areas of low melting point alloys:

1) In medical treatment, it is mainly used to make special-shaped radiation protection blocks.

2) It can be conveniently used for casting molds, producing special products for molds and casting.

3) For electronic and electrical automatic control, as thermal element, insurance material, fire alarm device, etc.

4) As a filler when bending metal pipes.

5) When making metallographic samples, it is used as a mosaic agent.

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What is the catalytic activity of gold nanoparticles as catalysts?

Regarding the catalytic properties of gold, the first ionization ability of gold is very large, and it is difficult to lose electrons, so the interaction force between gold and surface molecules is usually very weak. At temperatures below 200 °C, even highly reactive molecules, such as hydrogen and oxygen, are not easily adsorbed on the surface of single crystal gold. Since the adsorption of molecules on the catalyst surface is a prerequisite for the catalytic reaction, it can be considered that elemental gold does not have good activity for hydrogenation and oxidation reactions. Gold does not have very good catalytic activity. In fact, the prerequisite for the catalytic activity of gold catalysts is to prepare highly dispersed nano scale gold particles.

The characteristics of nano-gold catalysts: low temperature activity, good selectivity, and environmental friendliness.

An obvious feature of gold nanoparticles as catalysts is low temperature activity.

When the nano-gold catalyst catalyzes some reactions, it can be at room temperature or even below 0 °C, and the real good catalytic activity, such as catalytic CO oxidation and O3 decomposition, can be carried out at room temperature. In fact, the activity of gold catalysts for most reactions occurs below 230 °C. However, the activity of gold catalysts above 230 °C is significantly lower than that of other precious metal catalysts.

Nano gold particle catalysts have good selectivity when catalyzing certain reactions, and their catalytic properties are usually different from other noble metal catalysts.

For example, in the hydrogenation of CO2 catalyzed by Au/Zno catalyst, although its catalytic activity to methanol is slightly lower than that of commercial Cu/ZnO-Al2O3 catalyst, its selectivity is higher.

The nanogold powdercatalyst is environmentally friendly. Nano-gold catalysts can purify some polluted gases in the environment under normal temperature and humidity conditions without consuming too much thermal energy.

In terms of hydrogen energy generation, the catalyst can provide some new green synthesis methods and processing processes.

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High-fidelity 3D Color Printing Achieved by Photochromic Properties of Nano-tungsten Trioxide WO3

A few days ago, the Barcelona Institute of Technology (ICFO) published a discovery in Nano Letters: mixing nano-tungsten oxide particles with polyamide as a photosensitizer for color 3D printing can avoid the problem of discoloration in printing caused by traditional carbon-based photosensitizers , which contributes to the realization of high-fidelity 3D color printing.

 

In order to reduce cost and increase printing speed, selective sintering 3D printing usually incorporates photothermal sensitizers, which can accelerate the rate at which incident light is converted into heat. However, when printing white and color products, commonly used carbon-based photothermal sensitizers are used. Agents can cause discoloration of the work.

 

Previous ICFO related research has used gold-coated nanosilica microspheres to overcome the above problems (ie strong absorption in the near-infrared with minimal interaction with visible light). It turns out that while it works well in color printing, it has limitations when it comes to large gradation colorful high fidelity and pure white printing.

 

This time ICFO uses nano-tungsten oxide (WO3) as a photothermal sensitizer, which greatly reduces the production difficulty and material cost. It is colorless at high concentrations and has strong absorption in the near-infrared region, proving that they can convert light into heat at a very fast rate, making them a fast flux; UV light is effectively activated or deactivated; more importantly, they are stable at very high temperatures and have shown superior heating to color change rates compared to other sensitizers available. Finally, when mixed with other color inks, these nanoparticles were able to reproduce the same color as the original powder, maintaining the color purity of the original sample. This also opens up a new avenue for high-fidelity 3D color printing.