May 2015 – Silver Nanoparticles Antimicrobial,Copper Oxide Nanoparticles,Gold Nanopowder

May 26, 2015

Types of Chemical Heater and Silicon Carbide Whisker

Silicon Carbide is the only chemical compound of carbon and silicon. It was originally produced by a high temperature electro-chemical reaction of sand and carbon. Silicon carbide is an excellent abrasive and has been produced and made into grinding wheels and other abrasive products for over one hundred years. Today the material has been developed into a high quality technical grade ceramic with very good mechanical properties.It is used in abrasives,refractories,ceramics,and numerous high-performance applications. Silicon carbide whisker can also be made an electrical conductor and has applications in resistance heating, flame igniters and electronic components. Structural and wear applications are constantly developing.

Chemical heater and etch process are important terms that must be learned by people and businesses in the semiconductor industry. In this article, I am sharing about the types of chemical heaters used in the wet process system as well as the silicon nitride etch process.

Types of chemical heater

Quartz – Gas Heater — a system that is designed to meet the growing demand for heated high purity gasses. It has the capacity of heating a wide range of gases including: Ammonia (NH3), Helium (He), Argon (Ar), Hydrogen (H2), Arsine (AsH3),Hydrogen Bromide (HBr), Boron Trichloride (BCl3),Hydrogen Chloride (HCl), Carbon Dioxide (CO2), Nitrogen (N2),Carbon Monoxide (CO), Chlorine (Cl2), Nitrous Oxide (N2O), Oxygen (O2),Disilane (Si2H6), Sulfur Dioxide (SO2),Methylsilane (SiH3CH3)

Quartz – Fluid Heater — used in the semiconductor industry and its traditional application includes recirculation loop, either as the sole head source or a combination of a heated quartz tank.

SiC – HF & KOH Heater — designed for heating HF (hydrofluoric acide), KOH (potassium hydroxide), and other high PH chemistries. It uses high purity Silicon Carbide (SiC) as a heat transfer material because it has excellent heat transfer properties and eliminates the risk of contamination due to Teflon breakdown.
Interesting Facts about the Silicon Nitride Etch process

To be able to achieve the greatest etch rates and best selectivity, the phosphoric acid should have the highest ratio of water at a given temperature. For as long as the boil point is maintained, the etch rate of both Si3N4 and SiO2 can be precisely controlled.

Maintaining a boiling solution is one of the challenges in the etch process. When phosphoric acid is heated, the water solution begins boiling off. When temperature is not maintained, it affects the etching process as the acid concentration increase. Wet etch companies use a standard temperature controller to maintain temperature, but the water concentration will decrease and will change the etch rates. As a solution, wet etch process engineers use water addition system.

A technology called closed “reflux” system is used and it is created above the bath using condensing collar and a lid – this is to minimize water addition.

The chemical fumes and high temperatures that Nitride Etch tanks are subjected to are known to decrease bath life substantially by attacking the sealant that prevents liquid and fumes from entering the heater area. This problem has been addressed through the use of aquaseal.

Quartz Nitride Reflux system is engineered to address the unique needs of the silicon nitride etch process. It gives the following benefits to customers: process uniformity, lot-to-lot repeatability, prevents stratification.

May 11, 2015May 11, 2015

The Tern Nano-Technology Article

Some time ago I ran across the tern Nano-Technology while searching the net. According to Wikipedia, a brief description is “the control of matter on an atomic and molecular scale”. The Nano-scale is so small it is hard to imagine. To give you some idea a typical penny is about 19,000,000 Nano meters in diameter.

Even as small as it is, Scientists and Engineers have discovered how to manage and manipulate these tiny Nano Element Particles into some very useful and amazing new materials. The other amazing aspect of Nano-Technology is that when elements are reduced to a Nano-scale their physical characteristics change. Solids turn to liquids, stable materials turn combustible, insulators become conductors and opaque substances become transparent. With this knowledge there are and will be some amazing new products introduced into our daily lives.

Although most experts think that the changes brought about by this new science would improve our way of living, some are not so sure. I still continued my quest for new products and would do a search every so often just to see what was out there or what was new. During one of those searches, I ran across a company called Cermet Labs Inc. Their web site was very impressive and the information presented on the site was interesting. They made some claims that I am sure we have all heard before, however since it involved Nano-Technology I read on.

They seemed to have a variety of evidence to back up their statements about what their product would do. I considered the independent lab tests presented and the data on the field testing. It sounded reasonable and I decided to give them a call for more information. As it turns out they were located in a Detroit suburb which was within easy driving distance for me. I make an appointment and met with their CEO and Sales Manager. They made a very detailed presentation about the science behind their product. I understood some of it and some I did not. I guess wasn’t as concerned about how to build a watch, just could I get the correct time. The end result was that I felt it was a reputable company and product; however I still wanted to prove to myself that the claims were true.

The old seeing is believing theory. We went out to the parking lot and injected a 10ml syringe into the oil filler inlet of my car. I discovered later we really did not install it exactly as the instructions called for but it was in the engine now so I was anxious to see the results. Since I hadn’t kept actuate records on my mileage I decided I had better start so I could have a before number to compare to. When I started to keep track of my mileage the car had 205,427 miles on it. I though the car ran well and was getting reasonable mileage. During the first 636 miles the mpg was 21.18 which I though was not bad for a full size 96 Buick Park Avenue.

I was told that during the first 2000 miles of the run in period my mileage could vary. After 1912 miles I was pleased to find that my mpg was now at 25.14. Also it seemed that the car just ran smoother and had reasonably good power. I stopped keeping track for a while and just went about my normal driving. One day it seemed like I was going through a tank of gas quicker that usual. So I decided to check a tank full just to see if anything had changed. My odometer now read 213056 miles and the tank full of gas gave me 24.63 miles per gallon.

According to the EPA rating when the car is new, it should produce 17 and 27 highway. Considering the age and I believe I got this car miles mileage and the best performance is possible. I also believe that, the car’s performance and it is a ceramic ceramic processing laboratory reason. As a side note, I have to laugh when I saw a new car, claiming they will get 27 miles per gallon, $30000 worth of TV advertising. I can fill the tank at $30000 600. It is about 230000 miles.

May 4, 2015

Low Cost Synthesis of Silicon Carbide Nanopowders

Among modern ceramic materials, silicon carbide (SiC) and silicon nitride (Si3N4) has been successfully used in a variety of high-tech applications. SiC provides the effective combination of mechanical properties. It is widely used as an abrasive material and structure. It has high hardness, chemical inertness, than the melting temperature of the steel wear and oxidation of it for serious conditions such as high temperature sealing valve, rocket nozzle and wire drawing die and extrusion die for bearing applications because of its good wear resistance and corrosion resistance. In the tube by SiC to find its thermal properties and creep resistance of high temperature and hot electron exchange. The heating element from SiC. They can produce a high temperature of 1650 DEG C and medium in the air or inert considerable life. However, with any contact with water or hydrocarbon gas, can influence their age.

Silicon nitride has comparatively lower oxidation resistance and higher thermal conductivity than SiC. Major applications of silicon nitride are as automotive and gas turbine engine parts. It has high strength, fracture toughness and refractoriness which are required properties for ball bearings, anti-friction rollers. It performs remarkably when exposed to molten metal and/or slag.

A combined form of silicon carbide and nitride has been developed as silicon carbide grains bonded in silicon nitride matrix. This Si3N4-bonded silicon carbide is used for some critical applications where very high thermal shock resistance is required. For instance, in particular case of flame-out engine start-up, temperature reaches from ambient to 1600 °C in few seconds followed by an abrupt decrement to 900 °C in less than one second. Si3N4-bonded silicon carbide exclusively endures these conditions.

Traditional methods to produce these ceramic materials are energy intensive and hence expensive. For example, the Acheson process, which is the most widely adapted method to produce commercial-grade SiC, essentially takes 6 – 12 kWh to yield one kg of SiC. An inexpensive method, that uses low cost agro-industrial byproduct, is the pyrolysis of rice husks, first carried out by Lee and Cutler in 1975. Since then many researchers have discussed and used various process routes and modifications to obtain Silicon Carbide Nanopowders and/or silicon nitride, either in particulate or in whisker form, from rice husks.

Morphological studies on RH reveal that micron size silica particles are distributed in cellulosic part of RH. When these silica particles are made to react with carbon in biomass part of RH under specific experimental conditions, silicon carbide can result. Moreover, besides silicon carbide, modifications in process mechanism lead to formation of some other industrially useful products, viz. silicon nitride, silicon oxynitride (Si2N2O), ultra-fine silica, and solar-cell grade silicon.

Related reading: nano particles nano oxides