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Dispersion method of nano silver powder

Because of the volume effect, surface effect, quantum size and other effects unique to nanomaterials, nano silver powder has many special uses. In the field of antibacterial medicine, silver nano particles are more likely to be in close contact with pathogenic microorganisms, thereby exerting greater biological effects. It has the characteristics of wide antibacterial range and long duration, and is a new type of nano material with broad application prospects.

 

Nanopowders have small particle size and high surface activity, and it is easy to agglomerate between particles. Ag nano powder is no exception. The agglomeration will affect the development and application of nano Ag particle and its derivatives. The key technology is solve the agglomeration and obtain a stable dispersion. In order to obtain nano silver materials that are compatible with the process formula and are easy to disperse, please refer to the following points:

 

  1. If the user is willing to provide the application details, Hongwu Nano can modify the silver nanowires in advance to improve the dispersion of silver accordingly.
  2. In general, the addition of surfactants and mechanical dispersion methods should be combined to achieve good dispersion effects.
  3. Commonly used mechanical dispersing equipments include: generally used in low viscosity systems such as water and organic solutions, high-speed dispersing machines and ultrasonic equipment can be selected. High-viscosity system (paste) can be selected pulp mill, surface mill, high-speed dispersion disc, ball mill, etc..
  4. The dried silver powder can be depolymerized and surface modified with a supersonic jet mill.
  5. Commonly used surfactants: polymer surfactants such as PVP, gum arabic, polyethylene glycol, polyvinyl alcohol, etc. These dispersants are recommended for water-based systems. Surfactants can be used in combination and can significantly improve the dispersion effect.
  6. Based on years of silver powder production experience and users’ feedback, Hongwu Nano has summed up practical nano silver powder dispersion methods and techniques. Currently we can provide untreated nanosilver powder, surface-modified nano-silver powder, nano-silver water dispersion(colloidalAg), etc. Tailor-made nano-silver series products according to customer requirements.
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Application of Nano-silver Materials In The Field of Textile Functional Finishing Antibacterial, Antistatic, Anti-electromagnetic Radiation

The application of nano-silver materials to the field of textile functional finishing and the development of multi-functional, high-value-added fabrics will create huge economic and social benefits in the future textile industry. Nano-silver is a new type of nano-material that is under in-depth research and rapid development. It has broad application prospects in the textile industry due to its broad-spectrum and long-lasting anti-bacterial properties/anti-electromagnetic radiation properties/conductivity and absorption of some ultraviolet rays.

 

Application in natural fiber yarn and fabric

The fabrics made of natural fibers have good moisture absorption and are mostly porous fibers, which can provide enough water for the growth of bacteria. At the same time, the surrounding environment can also provide oxygen for the growth of bacteria and promote the reproduction of bacteria. Nano-silver has broad-spectrum and long-lasting antibacterial properties. At present, the antibacterial application of nano-silver in natural fibers is mainly for yarns and fabrics, and the antibacterial function is mainly obtained through finishing.

 

Nano-silver antibacterial finishing of yarn is generally aimed at cotton yarn or wool. For example, on the basis of puffing and pretreatment of cotton yarn with sodium hydroxide, tannic acid-reduced silver ammonia solution is used to load nano-scale silver particles in the micro gaps of the fiber to make The nano-silver particles and fibers are loaded on the yarn through coordination bonds, so that the silver-loaded cotton yarn has good antibacterial and washing resistance.

 

Under acidic conditions, using nano silver sol and acid dyes to dye wool yarns and antibacterial finishing at the same time, not only can improve the dye uptake, color fastness and flexibility of wool yarns, but also make wool yarns have good antibacterial properties.

 

 

According to reports, some scholars now use the reducibility and stability of the fabric itself to reduce the nano-silver particles in situ on the fabric, so that the fabric has good antibacterial and washing resistance. For example, Ma Tingfang uses the reducibility and dispersibility of cellulose macromolecules to reduce the silver nitrate solution in situ to prepare nano silver antibacterial cotton fabric, which has excellent antibacterial effect and washing resistance. After 20 cycles of washing, the antibacterial fabric will affect the large intestine. The inhibitory rates of Bacillus and Staphylococcus aureus are still as high as 98.5% and 94.3%, respectively. Majid Montazer and others also successfully used the reducibility and stability of cellulose to reduce Torrance reagent (silver ammonia solution) to synthesize nano silver. After the fabric treated with nano silver was washed for 30 times, the antibacterial performance was almost unchanged.

 

In addition, some scholars compound nano-silver with other substances, using inorganic-organic compounding method or inorganic-inorganic compounding method, to prepare compound such as nano-silver/polysaccharide quaternary ammonium salt (HACC), nano-silver/titanium dioxide, etc. Compound, and then padding and finishing the fabric to obtain functional textiles with multiple functions. Wang Haiyun prepared silver-loaded nano-TiO2 antibacterial agent in an inorganic-inorganic compounding method and used it for the finishing of cotton fabrics, so that the cotton fabric obtained the dual antibacterial functions of silver ion elution antibacterial and TiO2 photocatalytic antibacterial, and two kinds of antibacterial The effects promote each other, making the antibacterial effect far better than a single antibacterial agent with the same content.

 

Application in synthetic fibers and fabrics

Three types of synthetic fibers such as nylon, acrylic, and polyester are widely used. At present, the application research of nano-silver in synthetic fibers is mainly aimed at these three types of fibers and fabrics. The manufacturing of synthetic fiber functional fabrics mainly includes two methods: spinning functional fibers and finishing, specifically including blending spinning method, dipping (rolling) method and magnetron sputtering method. The direct-spun functional fiber has a long-lasting effect, but the technology is complex and the cost is high; the finishing agent is simple and convenient to use, and is suitable for most fiber textiles. The cost is low, but the washing resistance is relatively low.

 

(1) Blending spinning method

The blending spinning method is to add nano silver particles in the fiber manufacturing process to blend and spin the fiber to make the final fabric have corresponding functions. The blending spinning process has no pollution to the environment and is widely used. Zhang Hua uses ultra-fine hemp rod core powder to prepare nano silver particles and spun them into antibacterial multifunctional nylon. When the powder content is 2%, nylon fiber not only has excellent antibacterial properties, high strength, and good elasticity. , It also has the ability of far-infrared emission and negative oxygen ion release, and the spinnability also meets the requirements.

 

The antibacterial polyester masterbatch is prepared by blending the silver-loaded nano-zinc oxide antibacterial agent treated with T-aminopropyl triethoxysilane and polyester, which is added to the polyester skin layer, and the core-type antibacterial polyester is produced by spinning. This fiber has excellent antibacterial properties, and the sterilization rate of Escherichia coli and Staphylococcus aureus is above 99%.

 

(2) Dipping (rolling) method

Although the blending spinning method is environmentally friendly, it is difficult to prepare a spinnable spinning solution. In contrast, the dipping (rolling) process is relatively simple. Yu Qiaozhen treated the nano-silver particles to polyester fabrics by dipping, and studied its effect on the antistatic properties of the fabrics, and found that nano-silver treatment can effectively improve the antistatic capabilities of polyester fabrics; and different treatment methods have endless effects on the fabrics. Similarly, for example, the effect of the one-bath method in which nano-silver particle treatment and dyeing are performed at the same time is significantly better than the two-step method in which dyeing is followed by finishing.

 

Some researchers have explored a new type of finishing method that allows nano-silver particles to be bonded to the surface of the fiber through chemical bonding, so that the bond between nano-silver and the fiber is stronger. For example, the researchers amidoxim part of the acrylic fiber to make the fiber surface with chelating groups, which can be complexed with silver ions, and then use formaldehyde solution to reduce the silver ions to obtain nano-silver composite acrylic fiber. The killing rate of Staphylococcus aureus and Bacillus subtilis exceeds 99.99%, the antibacterial performance is good, and the original physical properties of the fiber have no obvious changes.

 

(3) Magnetron sputtering method

In order to avoid the waste liquid disposal problem of the dipping (rolling) method, some researchers used the radio frequency magnetron sputtering method to sputter nano-silver film on the surface of the fabric. The magnetron sputtering method is to charge a proper amount of argon in a high vacuum, and apply a DC voltage between the cathode (columnar target or flat target) and the anode (the wall of the coating chamber) to ionize the argon gas, and the argon ions are accelerated and bombarded by the cathode On the surface of the cathode target, the atoms on the surface of the target are sputtered and deposited on the surface of the substrate to form a thin film. This method has the advantages of strong bonding force between the coating layer and the substrate, and the coating layer is dense and uniform.

 

Application in industrial textiles

The application objects of nano-silver in industrial textiles are mainly non-woven fabrics, laminated composite fabrics and composite materials.

 

(1) Application in non-woven fabrics

The use of nano-silver to finish the non-woven fabric can obtain antibacterial properties and anti-electromagnetic radiation properties, which can be widely used in medical, sanitation, automotive interiors, electromagnetic shielding materials and other fields. Similar to synthetic fibers, the nano-silver finishing methods of non-woven fabrics also include blending spinning method, dipping (rolling) method and magnetron sputtering method, the principle of which is the same as described above. Hong Jianhan uses magnetron sputtering at room temperature to deposit nano-silver films on the surface of polyester spunbonded nonwovens to make the fabrics resistant to electromagnetic radiation. As the thickness of the nano-silver films increases, the shielding effect of electromagnetic waves is enhanced. This method expands the application field of nonwoven fabrics, and can be used to develop antistatic materials, conductive materials, electromagnetic shielding materials and fiber sensors.

 

The nano silver antibacterial agent is highly uniformly dispersed and implanted in the spinning solution to blend and spin, so that the fabric can obtain higher stability, antibacterial performance and washing resistance, and then obtain nano silver antibacterial spunlace nonwoven rolls and nano silver Antibacterial needle punched non-woven fabric rolls.

 

Its most extensive application field is the production of medical and sanitary products, such as nano-silver antibacterial masks, antibacterial wipes, medical bed sheets, medical wipes, etc. The latter’s market applications are also very broad, such as automobile compartment/indoor air conditioning antibacterial filter media, clothing linings, etc. , Antibacterial insoles, shoe materials, etc.

 

Application in laminated composite fabric

Laminated composite fabrics are ideal materials for civilian sportswear, cold-proof clothing, field work clothes, military combat uniforms, labor protective clothing and other products. The nano-silver finishing of composite laminated fabrics is mainly achieved by dipping or blending spinning. Researchers at Zhejiang Sci-Tech University used a cross-shaped cross-section polyester fiber material containing nano silver particles as an antibacterial modifier as the outer layer of the fabric, and combed cotton yarn with better moisture absorption as the inner layer of the fabric, using the changes in the fabric structure , Combined with advanced finishing technology, the fabric has multiple functions such as moisture absorption, perspiration, and antibacterial.

 

(3) Application in composite materials

 

The silver/polymer nanocomposite material not only has the excellent characteristics of nano silver and polymer, but also gives the material some new functions, so that it has broad application prospects in many fields such as textiles, electronics, and biomedicine.

 

Conclusion

As a new type of material, nano-silver is used in many fields, especially the textile industry is closely related to people’s lives, which has aroused the interest of many researchers. At present, the application of nano-silver in the textile industry is mainly to obtain antibacterial, antistatic, and anti-electromagnetic radiation functions. As people’s requirements for textile products increase, nano-silver will be increasingly used in functional fabrics, and its application prospects in the textile industry will become broader.

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The choice of the particle size of silver powder for conductive adhesive

With the rapid development of electronic technology, conductive adhesive, as a kind of electronic interconnection material, is increasingly used in surface packaging and chip interconnection. As a substitute for traditional Sn/Pb solder, conductive adhesive has the advantages of low curing temperature, simple process, and environmental protection.

 

Conductive adhesive is an adhesive formed by dispersing conductive particles in a resin matrix. After curing and drying, it has conductive properties similar to metals. It has a certain bonding performance. By bonding different conductive materials together, a conductive path is formed between these materials to conduct electricity. Before curing, the conductive adhesive is a paste-like glue that can flow, and can be cured by heating and ultraviolet light, and the cured product meets certain properties, such as stable electrical conductivity and certain shear strength.

 

According to the conductive mechanism of conductive adhesive, the general selection principle is: more contact area can be formed between particles. There are many shapes of silver powder, such as flake, spherical, dendritic, irregular shape, etc. Different silver powders can be selected according to different uses. Generally, flake silver powders are mostly used in conductive adhesives, and the diameter is usually between 1-10um. Hongwu Nano can customize different specifications, such as the particle size, SSA, apparent density, of flake conductive silver powder for customers. For example, the flake silver used for LED dispensing and touch screen circuits has key differences in parameters and performance.

 

HONGWU is the first domestic manufacturer of large-scale and specialized production of silver powders. This series of products include: nano antibacterial silver powder, conductive flake silver powder, bright silver powder, conductive spherical silver powder, ultrafine silver powder, flake silver-coated copper powder, spherical silver-coated copper powder, dendritic silver-coated copper powder. Hongwu Nano has many years of professional and technical personnel engaged in the research and development and production of nano powders to provide technical support for the enterprises. At the same time, the company has established close cooperative relations with many domestic and foreign universities and research institutions to ensure the sustainable development of the company. Hongwu currently has an annual production capacity of 3 tons of nano silver powder and 5 tons of conductive silver powder. https://www.hwnanomaterial.com/

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The Application Of Nano Silver Antibacterial In Clinical Treatment

Nano silver powder is a new type of antibacterial product developed based on nanotechnology. Due to the quantum effect, small size effect and large specific surface area, it has an antibacterial effect that traditional inorganic antibacterial agents can’t match. It has high safety and long-lasting effectiveness. , Is an antibacterial agent with long-lasting and weather resistance.

Regarding the principle of the bactericidal effect of nano-silver, most scholars believe that the specific surface area of ultra-fine silver is very large and presents AG+ in water. Therefore, the bactericidal effect of nano-silver is mainly related to silver ions, which can be related to the -SH in the enzyme protein in the bacteria. It binds quickly to inactivate key metabolic enzymes, making pathogenic bacteria unable to metabolize and die; secondly, nano-silver can bind to DNA bases of pathogenic bacteria and form cross-links to replace hydrogen bonds between adjacent nitrogens in purines and pyrimidines. Which denatures DNA without being able to replicate, leading to inactivation of pathogenic bacteria. The atomic arrangement of nano-silver shows that it is a “medium state” between solid and molecule. This extremely active nano-silver particle has super antibacterial ability and can kill bacteria, fungi, mycoplasma, chlamydia and other pathogenic microorganisms. In addition, nano-silver is a non-antibiotic bactericide, and no bacteria are resistant to nano-silver.

1. Application in burns, scalds, burn skin grafts
The results of skin grafting for dozens of burn patients showed that nano-silver increased the epithelialization rate of reticuloepithelial grafts by 40%, and had a better effect on promoting repair of residual burn wounds. The healing time of the experimental group was significantly shorter than that of the control group. Researchers believe through clinical observations and animal experiments that nano-silver antibacterial medical dressings are a kind of clinical external medicine for burns with strong anti-infective effect, low absorption, small toxic and side effects, and convenient use.

2. Application in dermatology
Nano silver is effective in treating acne vulgaris. The nano-ulcer patch is used to treat I-II bedsores. In comparison with the control, it is found that the active ingredient of the nano-ulcer patch is nano-silver particles, which has super permeability, produces a biothermal effect, improves the microcirculation of the damaged tissue, and eliminates the local area. Edema is conducive to tissue regeneration and wound healing.

3. Application in dentistry
Nano silver antibacterial agent can be used to prevent oral caries and mucosal diseases, and can also solve the problem of easy pollution during the production and use of dental materials.

In summary, due to its quantum effect, small size effect and large specific surface area, nano-silver materials are easily in close contact with pathogenic microorganisms, thereby exerting greater biological effects, so they have high safety, wide antibacterial range, and continuous Advantages such as long sterilization time. However, nano-silver materials are prone to particle aggregation and lose their nano-characteristics under conventional conditions without protective agents, which will affect the antibacterial effect of nano-materials. Therefore, the packaging and storage of nano-silver are also extremely important. For details, please consult Hongwu Nano staff online our website:https://www.hwnanomaterial.com/.

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Four common metal conductive powders

Conductive materials can conduct current well because they have a large number of charged particles that can move freely under the action of an electric field, including conductor and superconducting materials.

The following are the four most widely used metal conductive materials.

Pure silver conductive powder (Ag99.99%)

1) Flake:

Common available particle size: <1um, 1-3um, 3-5um, 5-8um, 8-10um, particle size, and apparent density can be customized according to requirements. Flake silver powder with low apparent is available.

Appearance: silver gray with metallic luster

Application: Flake silver powder is a high-performance conductive filler material with good oxidation resistance. Flake Ag particle is the main raw material for making conductive coatings, membrane switches, conductive inks, conductive rubber, conductive plastics, and conductive ceramics.

Flake Ag powder is an ideal raw material for good low-temperature polymer slurry, conductive paint and electromagnetic shielding paint. The coating prepared with flake silver powder has good fluidity, anti-settling and large spray area.

2) Spherical silver conductive powder:

Common particle size: <1um, 1-3um, 3-5um，5-8um，etc

Application: Near-spherical silver powder is mainly used as conductive filler for high-temperature sintered conductive paste.

There is no absolute standard for silver powder as a conductive filler. The choice of silver powder should be based on the corresponding adhesive, the target conductor material, the physical and chemical properties of the film, and the reliability requirements.

 

Silver coated copper conductive powder (common particle size is 1-3um, 3-5um, 5-8um, 10um, Ag content ranges from 3%-35%)

Features:

1) Silver coated copper powder has adjustable superfine particle size.

2) Ag coated Cu powder has several shapes, such as spherical, flake, dendritic, etc.

3) Silver-coated copper powder has excellent conductivity and lower cost, which can replace some applications of pure silver powder.

4) Silver-coated copper powder has good oxidation resistance and dispersion, and can be used in medium and low temperature slurry.

Application range: It can be widely used in conductive adhesives, conductive coatings, polymer pastes, and various industries that require electrical conductivity and static electricity, electromagnetic shielding, and surface metallization of non-conductive materials.

Silver-coated copper powder can be widely used in conductive adhesives, conductive coatings, polymer pastes, and various fields of microelectronics technology that need to conduct electricity and static electricity, and non-conductive materials surface metallization. It is a new type conductive composite powder. Ag-Cu powder is widely used in the fields of electrical conductivity and electromagnetic shielding in various industries such as electronics, electromechanics, communications, printing, aerospace, and military industries, such as computers, mobile phones, integrated circuits, various electrical appliances, electronic medical equipment, electronic instruments, etc., so that products are not interfered by electromagnetic waves, while reducing the harm caused by electromagnetic radiation to the human body, as well as the conductivity of colloids, circuit boards, and other insulators, to make the insulated object have good electrical conductivity.

 

Pure copper powder (Cu 99%+)

Common particle size: <1um, 1-3um, 3-5um, 5-8um, etc.

Features: spherical and flake shape, uniform particle size, good dispersion, high crystallinity

Applications: Manufacture of terminals and internal electrodes of multilayer ceramic capacitors(MLCC), electronic components and electronic pastes, etc.

Pure nickel powder (Ni 99.7%): Common particle size: 1-3um

As a functional conductive filler, nickel powder can be added in coatings, adhesives, inks, plastics, rubbers, and can be made into conductive, electromagnetic shielding, anti-static  products, to be used in electronics, electromechanics, communications, printing, aerospace, weapons and other industrial sectors in the field of electrical conductivity. Such as computers, mobile phones, electronic medical equipment, electronic instruments and meters.

Guangzhou Hongwu Material Technology Co., Ltd. supplies the conductive materials mentioned above, with reliable high and stable quality, reasonable prices and excellent customized service.

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The Global Market’s Demand for Nano Silver is Growing Rapidly

At present, nanotechnology is considered to be the most revolutionary technology, which has had a significant impact on social livelihoods through its multidisciplinary applications. Silver nanoparticles (AgNPs) is a metal nanoparticle material that has been widely researched and applied. At present, the global market’s demand and enthusiasm for silver nanoparticles (AgNPs) continues to increase.

Chinese scholars have discovered a new strategy of highly effective antibacterial nano-silver, sterilization does not produce drug resistance.

Professor He from the School of Chemistry and Chemical Engineering of Hefei University of Technology and Professor Cha from the School of Food and Bioengineering have successfully developed a nano-silver aqueous dispersion with weak acid response recombination function, which can be sprayed on the wound to achieve an efficient target for drug-resistant bacterial infections For treatment, it eliminates bacteria while not producing resistant bacteria, and thus proposes a new high-efficiency antibacterial strategy. Relevant results were published online in the “Advanced Functional Materials” magazine a few days ago.

Scientists hope that a material that they claim can kill bacteria and viruses can be used in masks to help deal with the new coronavirus pneumonia epidemic.

The main component of this material is nano-silver with antibacterial properties, which is prepared by using a melt-blown process. Alexander Zanovich Medvedev, who worked on the project, explained that this made polypropylene fibers with a diameter of 1 micron. Medvedev is currently in charge of the work of a laboratory of the Siberian branch of the Russian Academy of Sciences. It is not clear whether this research has been published in a peer-reviewed journal.

Medvedev said in a statement that he and his colleagues put the finished material on the inner layer of a conventional three-layer medical mask. The chief researcher of the Institute of Chemistry and Technology Nikolai Zakharovich Liakhov said that the researchers tested the performance of the mask against influenza A virus, staphylococcus and E. coli.

When the research team compared this new material with the material of ordinary masks, it was found that the number of viruses passing through the latter was 10,000 times higher.

Nano-silver medical masks, using new nano silver antibacterial patented technology, developed and created the first reusable nano-silver non-woven medical masks in Guangdong Province. Based on the calculation of continuous wearing for 8 hours a day, the life cycle of a nano-silver non-woven mask can reach 7 days.

In addition to the conventional single-layer spunbonded non-woven fabric on both sides of the inside and outside, and the middle melt-blown non-woven fabric, the mask also contains a layer of nano-silver non-woven fabric, which has strong water absorption, releases high-activity silver ions, and kills bacteria and viruses. When breathing moist gas, it will release silver ions for a long time to kill bacteria.

The test results of the Hong Kong Polytechnic University wearing experiment show that after 8 hours of wearing, the total number of bacteria on the surface of this type of mask is still far below the range allowed by the national standard, and it can be used repeatedly; the test report of the NELSON laboratory approved by the US FDA shows that the The bacterial filtration rate of the type mask is over 99.7%. After 18-24 hours of continuous use, its bacterial content still does not exceed the range allowed by the national standard, and it can be used repeatedly for a long time.

The research team of Shanghai University has developed 6Cr16MoMA ultra-high hardness stainless steel containing nano-antibacterial silver, which has high strength plastic toughness and sterilization function. The core technology has been authorized by the national invention patent.

In 2017, the Antibacterial Material Testing Center of the Institute of Physics and Chemistry of the Chinese Academy of Sciences tested the antibacterial properties of the material and found that the antibacterial rates for E. coli and Staphylococcus aureus were both ≥99%. In 2019, after further testing by Shanghai Ingeer Testing Technology Service Company, the material has an antibacterial rate of 99.61% against Candida albicans and an antibacterial rate of Pseudomonas aeruginosa ≥99.99%. This stainless steel material not only has a high antibacterial rate, but also has excellent mechanical properties. It is used in the production of household kitchen knives. Its cutting performance is equivalent to that of high-end imported kitchen knives. It is much better than similar domestic products and is at the leading domestic level. Get latest nano silver price from https://www.hwnanomaterial.com.

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Silver nano powder market is expect a fast growth

Nowadays natural resources are far not enough to meet applications need, especially when it comes to high-tech and high-end products and rise new market needs.
Today we’ll discuss the market growth of a high-tech raw material silver nano powder.

1.Silver nano powder is widely used in the electronic industry: High-end silver paste (glue) chip components for external electrode pulp; thick film integrated circuit pulp; solar cell electrode paste, LED chip package with conductive silver plastic; used in printed electronic devices such as conductive ink, etc. The growth of electronic industry will help the growth of silver nano powder.

2.Silver nano powder is widely used for antibacterial. Since silver nano powder’s lasting and special antibacterial function, it is applied to produce antibacterial products: antibacterial Medicine and medical equipment; antibacterial plastic, rubber products, textiles and clothing footwear; antibacterial coatings, ceramics and glass; green antibacterial coatings green home appliances and furniture products etc. More and more manufacturers use silver nano powder to meet market antibacterial need and trend, also take it as a selling point, which customers will buy.

3.Silver nano powder as catalytic, materials Ethylene oxidation reaction catalyst, fuel cell with a supported silver catalyst New energy heat exchange material, etc. Since the small size and high specific surface area, silver nano powder is widely used as catalyst.

In the past years, many researchers are made to explore and testing special applications of silver nano powders in different areas. And now many of them has proved to work good and detailed application technology has get matured. Together with the industries it applied for grows fast. To conclude, silver nano powder are expected a fast growth.

Related reading:silver nanoparticles uses    antibacterial activity of silver nanoparticles    

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Silver Nanopowder and Silver Nanowires Application Guide

Silver Nanoparticle application guide:
Common stirring to disperse the silver nanopowder is very difficult. At least more than 30 minutes with an ultrasonic disperse. Using pvp coated or a fatty acid coated is just in order to improve the dispensability of the silver powder. Generally based on customer requirements have been handled well in advance, and then customer can be used directly. Unmodified silver nanopowder’s dispersion, generally need to add some non-toxic surfactants, such as washing fruits and vegetables detergent. Before to disperse pvp-coated silver nanopowder, it is suggested to wetted with ethanol and then add water to stir, without affecting the customer process, add a few drops detergent mixing, the effect is also very good.

Silver Nanowires application guide:
Generally we maintain silver nanowires inventory in powder form. We could also maintain dispersed in ethanol or IPA. Just depends on the customer required. Shipments in solvents may require additional lead time. We can provide silver nanowires in different concentration according to customer request. The solvent include ethanol, isopropanol, diethylene glycol, water, terpineol and so on. And silver nanowires is very stable, not easy to be oxidized, could use it under the room temperature. But after open it, please sealed it up at soon as possible so that will not affect the powder quality when exposed to the air in long time.

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The Extinction Spectra of Silver Nanopowders Arrays

Influence of Array Structure on Plasmon Resonance Wavelength and Width
We use high-quality electrodynamics methods to study the extinction spectra of one-dimensional linear chains and two-dimensional planar arrays of spherical Silver Nanopowders, placing emphasis on the variation of the plasmon resonance wavelength and width with array structure (spacing, symmetry), particle size, and polarization direction. Two levels of theory have been considered, coupled dipoles with fully retarded interactions and T-matrix theory that includes a converged multipole expansion on each particle. We find that the most important array effects for particles having a radius of 30 nm or smaller are captured by the couple dipole approach.

Our calculations demonstrate several surprising effects that run counter to conventional wisdom in which the particle interactions are assumed to be governed by electrostatic dipolar interactions. In particular, we find that for planar arrays of particles with polarization parallel to the plane the plasmon resonance blue shifts as array spacing D decreases for D larger than about 75 nm and then it red shifts for smaller spacings. In addition, we find that the plasmon narrows for D > 180 nm but broadens for smaller spacings.

The results can be rationalized using a simple analytical model, which demonstrates that the plasmon wavelength shift is determined by the real part of the retarded dipole sum while the width is determined by the imaginary part of this sum. The optimal blue shifts and narrowing are found when the particle spacing is slightly smaller than the plasmon wavelength, while red shifts and broadening can be found for spacings much smaller than the plasmon wavelength at which electrostatic interactions are dominant. We also find that the array spectrum does not change significantly with array symmetry (square or hexagonal) or irradiated spot size (i.e., constant array size or constant particle number).