Sunday, March 19, 2017

Babbitt Material PPT

An alloy is a mixture of metals, or a mixture of metal and another element. White metal alloys are those which are light-coloured and generally have a lead or tin base. These alloys are also known as Babbitt metal, or bearing metal, a term which is generally preferred over ‘white metals’. Babbitt metal can be one of several alloys used as a bearing surface in a plain bearing.
Babbitt metal was first created by Isaac Babbitt, from whom it takes its name, in 1839. The original formula for his bearing metal was 89.3% tin, 7.1% antimony and 3.6% copper. This formula is still used by some manufacturers today and marketed as ‘Genuine Babbitt’, or ASTM B-23 Grade 2 Babbitt. It is a soft, white non-ferrous alloy which is used to provide a bearing surface. Bearings are used in engines to support moving mechanical parts and protect them from frictional degradation. Babbitt metal also has properties that help it reduce friction which makes it a good material for use in a plain bearing.
Babbitt metal is soft and can be easily damaged if not treated correctly. This would make it seem unsuitable for use as a bearing surface, however, the structure of the alloy is made up of small, hard crystals which are dispersed in a matrix of softer alloy. This means that as the bearing wears down, the harder crystal is exposed and a path for the lubricant is provided.
Babbitt bearings work by providing a low coefficient of friction, principally achieved by 2 means. First, there is the fact that the bearing itself has a low coefficient of friction so even without lubrication, a Babbitt bearing will have much less friction than another metal such as steel or cast iron. However, by adding lubrication Babbitt bearings can have a significantly low coefficient of friction – even lower than ball bearings.
Until the mid-1950s poured Babbitt bearings were a common feature of automotive appliances. Tin based Babbitts were commonly used as they could stand up to the impact of the connecting rods and crankshaft. Babbitt bearings were also commonly used in factories, before the invention of low cost electrical motors, to distribute power throughout via a central engine. Today, Babbitt is more commonly used as a thin layer covering bearings made of replaceable steel so that it still acts as a bearing surface.

Saturday, March 18, 2017

Biomass Energy PPT

Bioenergy draws on a wide range of potential feedstock materials: forestry and agricultural residues and wastes of many sorts, as well as material grown specifically for energy purposes. The raw materials can be converted to heat for use in buildings and industry, to electricity, or into gaseous or liquid fuels, which can be used in transport, for example. This degree of flexibility is unique amongst the different forms of renewable energy.
Biomass can be converted into electric power through several methods. The most common is direct combustion of biomass material, such as agricultural waste or woody materials. Other options include gasification, pyrolysis, and anaerobic digestion. Gasification produces a synthesis gas with usable energy content by heating the biomass with less oxygen than needed for complete combustion. Pyrolysis yields bio-oil by rapidly heating the biomass in the absence of oxygen. Anaerobic digestion produces a renewable natural gas when organic matter is decomposed by bacteria in the absence of oxygen.
Different methods work bet with different types of biomass. Typically, woody biomass such as wood chips, pellets, and sawdust are combusted or gasified to generate electricity. Corn stover and wheat straw residues are baled for combustion or converted into a gas using an anaerobic digester. Very wet wastes, like animal and human wastes, are converted into a medium-energy content gas in an anaerobic digester. In addition, most other types of biomass can be converted into bio-oil through pyrolysis, which can then be used in boilers and furnaces.

Wednesday, March 15, 2017

Ceramic Bearing PPT

Ceramic bearings are typically constructed with a ferrous inner and outer ring or race with ceramic balls in the place of steel. Ceramic bearings offer many advantages over all steel bearings, such as higher speed and acceleration capability, increased stiffness, lower friction and more. Ceramic balls are also nonconductive. Ceramic bearings are available in all standard industry configurations such as, angular bearings, thrust bearing, pillow block bearing, needle bearings, and roller bearings.

Ceramic bearings balls are typically made from (Si3N4) ceramic silicon nitride and have greater hardness than steel balls resulting in longer ball life. Ceramic bearing balls have smoother surface finishes than most steel bearing balls. Thermal properties are also better steel balls which result in less heat generation due to friction at high speeds. To manufacture a extra fine surface finish on ceramic balls, the balls are elevated with a magnetic field and then polished with plasma stream. Ceramic bearings balls are rated at higher spin rates than steel bearing balls.

Ceramic bearing balls can weigh up to 40% less than steel ones, depending on size and material. This reduces centrifugal loading and skidding, so hybrid ceramic bearings can operate 20% to 40% faster than conventional bearings. This means that the outer race groove exerts less force inward against the ball as the bearing spins. This reduction in force reduces the friction and rolling resistance. The lighter balls allow the bearing to spin faster, and uses less energy to maintain its speed.

While ceramic hybrid bearings use ceramic balls in place of steel ones, they are constructed with steel inner and outer rings; hence the hybrid designation. While the ceramic material itself is stronger than steel, it is also stiffer, which results in increased stresses on the rings, and hence decreased load capacity. Ceramic balls are electrically insulating, which can prevent 'arcing' failures if current should be passed through the bearing. Ceramic balls can also be effective in environments where lubrication may not be available (such as in space applications).

Ceramic bearing balls require less lubricant and exhibit less lubrication degradation, which results in increased bearing life. Ceramic bearings manufactured from Si3N4 can operate at temperatures up to 1600F. Ceramics also are resistant to oxidation.
Typical applications for ceramic bearings:

High temperature applications, friction, high speed, aircraft accessory, semiconductor and food processing, dental hand piece turbines. Many high speed electric motors requiring voltage isolation use ceramic material bearings.

Agile Manufacturing PPT

Agile manufacturing is an approach to manufacturing which is focused on meeting the needs of customers while maintaining high standards of quality and controlling the overall costs involved in the production of a particular product. This approach is geared towards companies working in a highly competitive environment, where small variations in performance and product delivery can make a huge difference in the long term to a company's survival and reputation among consumers.

Need of Agile manufacturing in a company

  1. Customer-integrated process for designing, manufacturing, marketing, and supporting all products and services.
  2. Decision making at functional knowledge points not in centralized management “silos”
  3. Stable unit costs, no matter what the volume
  4. Flexible Manufacturing-ability to increase or decrease production volumes at will.
  5. Easy access to integrated data  whether it is customer-driven, supplier-driven, or product and process-driven
  6. Modular production facilities that can be organized into ever changing manufacturing nodes.
  7. Data that is rapidly changed into information that is used to expand knowledge.
  8. Mass customized product verses mass produced product. 

Agile Manufacturing enterprises will be capable of rapidly responding to changes in customer demand.  They will be able to take advantage of the windows of opportunities that appear in the market place.  With Agile Manufacturing we will be able to develop new ways of interacting with our customers and suppliers.  Our customers will not only be able to gain access to our products and services, but will also be able to easily assess and exploit our competencies, so enabling them to use these competencies to achieve the things that they are seeking.

Wednesday, March 8, 2017

Carbon Foam Military Application PPT

Coal-based carbon foams are a new structural material made in a cost-effective proprietary process. The result is an inexpensive, lightweight, fire-resistant, impact-absorbing material that can be thermally insulating or conducting, and whose electrical resistivity can be varied over many orders of magnitude. Coal-based carbon foams offer systems designers alternatives to current design materials, extending the performance ranges in material systems where they replace more conventional materials whose peak performance levels have already been reached. With its ease of use, coal-based carbon foams can be cut, milled and turned with conventional equipment and tooling. Integration with other materials including impregnation with phenolic or other resins, and lamination with Kevlar or other laminates, is straight-forward, creating a broad spectrum of potential applications to defense, aerospace and commercial markets.

Wednesday, March 1, 2017

No ink required: Printing Paper With Light

One of the biggest problems in the world is waste. As the trend in globalization and modernization grows at a rapid pace, its effects on the environment becomes inevitable. The increase in population density has given rise to a number of problems that will take more than a century to solve.Over the years, the amount of plastic production has been reduced by transforming disposable materials into paper and wood.
However, this may have created another issue, which is not too easy to resolve. Scientists have been thinking of ways to reduce the amount of paper waste and have come up with an interesting solution: rewritable paper. We have heard of erasable ink, but rewritable paper is a first.
A special dye embedded in the paper makes it printable and rewritable. The dye goes from dark to clear and back when chemical reactions move electrons around. (Electrons are the subatomic particles that orbit in the outer regions of an atom.) The paper’s color-change chemical undergoes what are known as redox reactions. Redox is short for reduction and oxidation.
Oxidation steals one or more electrons from a molecule. Rust is an example of oxidation. “When iron rusts in air, its electrons move to nearby oxygen atoms,” explains Yadong Yin. He’s a chemist at the University of California, Riverside. Reduction is the opposite of oxidation. It adds one or more electrons. As rust oxidizes iron, the process reduces those nearby oxygen atoms. That means that they gain electrons, which have a negative charge.
When dye in the new paper is oxidized, it appears blue, red or green. (What color depends on which dye is in the paper.) When the dye on some parts is reduced, color on those areas disappears. Controlling these two reactions makes it possible to print on, erase and reuse the new paper.
The starting base of the “paper” used in the study was a clear plastic. That allowed it to show how the paper works. But the technology also could be used with glass or conventional paper — the type made from wood pulp — as long as each contains the redox dyes and the other chemically active components.
Photocatalytic Color Switching of Transition Metal Hexacyanometalate Nanoparticles for High-Performance Light-Printable Rewritable Paper
Developing efficient photoreversible color switching systems for constructing rewritable paper is of significant practical interest owing to the potential environmental benefits including forest conservation, pollution reduction, and resource sustainability. Here we report that the color change associated with the redox chemistry of nanoparticles of Prussian blue and its analogues could be integrated with the photocatalytic activity of TiO2 nanoparticles to construct a class of new photoreversible color switching systems, which can be conveniently utilized for fabricating ink-free, light printable rewritable paper with various working colors. The current system also addresses the phase separation issue of the previous organic dye-based color switching system so that it can be conveniently applied to the surface of conventional paper to produce an ink-free light printable rewritable paper that has the same feel and appearance as the conventional paper. With its additional advantages such as excellent scalability and outstanding rewriting performance (reversibility >80 times, legible time >5 days, and resolution >5 μm), this novel system can serve as an eco-friendly alternative to regular paper in meeting the increasing global needs for environment protection and resource sustainability.
Various samples of the light-printable paper. Credit: Wang et al. ©2017 American Chemical Society
The paper starts out with all of the dye oxidized, and therefore colored. Nano-scale crystals of titanium dioxide — each around a billionth-of-a-meter in size — cover the paper’s surface. To print something, scientists cover this solid-color paper with words or an image printed on a see-through base. You might think of it as a stencil, or mask. Next the scientists expose the masked surface with ultraviolet (UV) light. The light triggers a reduction reaction on sections of the paper not shaded by the printing. So it removes color from those sections.
Only the oxidized parts that had been covered by the stencil stay dark, explains Yin. Those areas become the “printing.” So the writing is done chemically, using light. The process chemically reduces dye in all of the areas that should be blank space.The tiny size of the surface nanocrystals lets electrons move easily out of them and into the dye. In effect, Yin explains, when the crystals are exposed to the UV light, “electrons are kicked out.” Afterward, other organic materials in the paper give up electrons. Those electrons fill “holes” made when electrons left the molecules of titanium dioxide. Now the nanocrystals can work again.
To start over, the paper needs to turn back into a solid-colored sheet. Oxygen in the air makes this happen. That oxygen pulls electrons from the “unprinted” areas. But you don’t want this happening seconds after you write on the paper. People need time to read the printing first! Special cellulose in the paper slows that erasure. Among other things, this cellulose makes it hard for oxygen to react with the dye. Printing can remain visible for two days or so, Yin’s research team has shown. On the flip side, some people may want to reuse the paper right away. Heating speeds the erasure time. At the right temperature, oxidation can return the entire paper to its solid color in five minutes or less. Yin’s team at UC-Riverside describes its new, rewritable paper in the Dec. 2, 2014, issue of Nature Communications.

Yin’s group smartly chose ingredients for the new technology so that it will operate well, says Howon Lee. This makes the new paper “significant,” he says. In other words, the paper can be printed on. It doesn’t turn dark again immediately. And the paper can be reused.Lee is an engineer at Seoul National University in Korea and did not work on the new paper. But he knows Yin’s work. In fact, Lee worked with Yin and other scientists in 2009 on another project. That study explored how light interacts with nanostructures. This happens naturally on butterfly wings and peacock feathers. That team wanted to learn more about the science of this natural process. The group published its findings in Nature Photonics.Yin’s current project is “more like a delicate engineering work,” Lee now says. It does explore some basic science. But beyond that, he explains, it puts science principles to work. “The rewritable paper project aims to help people in real life,” Lee says. The paper can work with blue, green or red dye. But full color printing is not yet practical. To do that, scientists need a way to use a combination of dyes. They also will need to vary how much light different parts of the paper get during printing.Another issue is that someone couldn’t read an article and then decide to save it on the new paper. The whole paper still would darken in two days or so.
Nonetheless, the cost savings and environmental benefits of rewritable paper could be “enormous,” Yin says. Lower paper use could help preserve forests. Yin also argues that using less paper not only could reduce the amount of trash from printed materials, but also the amount of chemical pollutants.

More information: Wenshou Wang et al. "Photocatalytic Color Switching of Transition Metal Hexacyanometalate Nanoparticles for High-Performance Light-Printable Rewritable Paper." Nano Letters. DOI: 10.1021/acs.nanolett.6b03909

Saturday, February 18, 2017

Researchers Invent New Solar-Powered Technology that Purifies Dirty Water 160 Times Cheaper than Existing Ones

Water is one of our basic necessities, but as we have consistently reported, the situation on water accessibility around the world is very dire.

According to United Nations statistics, more than 2.9 billion people in 48 countries will face water shortages in the next 10 years. Water experts say it could destabilize and jeopardize the existence of some nations.

Particularly with clean drinking water, the statistics are appalling.  Over 1 billion people worldwide get their drinking water from unimproved sources including lakes, rivers, dams, springs and unprotected dug wells. The consequences of drinking from these sources is most likely death. Water-related disease kills around 840,000 people annually. Women and children are said to spend more than 140 million hours a day collecting usable water, which is more often than not from contaminated sources.

To solve this obvious problem, we need an impressive innovation that will ensure we no longer fully depend on our traditional sources for water. Or, if even we would depend on it, we should purify the dirty water many people are drinking around the world to avert disease and death.

Therefore, many researchers around the world have worked around the clock to help mitigate the problem. In the recent past, some researchers have invented resourceful technology to help solve the growing water problem. More researchers are still coming out with their inventions.

A group of researchers have announced in a new study, the invention of a new solar-powered water purifier that is cheaper than the existing ones. The raw materials needed to construct the solar still technology cost just $1.60 per square meter. Similar existing water purifiers can cost up to $200 per square meter.

Apart from the price, this solar still is said to be four times faster and more effective than its already available competitors. Solar stills have been around for years, with most being simple black-bottomed vessels filled with water, and topped with clear glass or plastic. Sunlight absorbed by the black material speeds evaporation, which is trapped by the clear topping and funneled away for drinking water. Most pollutants don’t evaporate, and so are left behind. But much of the sun’s energy is wasted in the slow heating of a full vessel of water. Even the best stills need to be around 6 square meters in size to produce enough water for a single person for one day.

To make the technology efficient, researchers have attempted two things. First, they designed their stills so that only the very top layer of water in the vessel is heated and evaporated, which means less energy is lost. Second, they’ve turned to nanomaterials to absorb more of the sun’s rays. However, efficient light-absorbing nanomaterials can cost hundreds of dollars per gram, making them unrealistic for widespread use in developing countries where the technology is needed the most.

However, Qiaoqiang Gan, an electrical engineer at the State University of New York (SUNY) in Buffalo realized the cost of the nanomaterials, and wanted a cheap alternative. Gan is the lead author of the latest study.

With a block of polystyrene foam and a fiber-rich paper – similar to the paper used to make currency – Gan and his research team produced a new super-cheap device. According to the researchers, their technology is not only cheap, but is also 88% efficient, channeling energy it traps from the sunlight into the evaporating water. This allows a 1-square-meter-sized device to purify 1 liter of water per hour, which is about four times faster than already commercially available versions.

Using extremely low-cost materials, we have been able to create a system that makes near maximum use of the solar energy during evaporation. At the same time, we are minimizing the amount of heat loss during this process,” Gan said.

The technology will “allow people to generate their own drinking water much like they generate their own power via solar panels on their house roof,” said Zhejun Liu, a visiting scholar at SUNY Buffalo who also took part in inventing the technology.

According to the estimate, providing the minimal water needed for a family of four, with this new technology, would cost as little as $5 for the raw materials per device. The cheap cost may not only help people in impoverished regions, but also help aid workers deploy cheap water purifiers to people affected by natural disasters which wipe out safe drinking water sources.

The researchers have presented their technology paper in the journal Global Challenges. The researchers announced the formation of a company called Suny Clean Water to commercialize their technology; further adding they’re already in discussions with other companies around the world to make the technology available, especially in developing countries where it is needed the most.