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帖子主题：Hot Zone Design for Vacuum Furnaces

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发表于 2012/11/19 11:15:30	楼主

Hot Zone Design for Vacuum Furnaces

Hot Zone Design for Vacuum Furnaces

Hot Zone Design for Vacuum Furnaces

Insulation/Heat Shield

Molybdenum and graphite are also used for vacuum-furnace insulation. In an all-metal hot zone the heat-shield package is made up of multiple layers of sheet metal with spaces between each layer (Fig. 3). In a standard furnace with a maximum 1315°C (2400°F) operating temperature, the heat shielding often consists of two layers of molybdenum sheet backed by three layers of stainless steel sheet. For higher operating temperatures, the number of molybdenum layers is increased as well as the thickness of each layer. For very high operating temperatures over 1650°C (3000°F), tantalum sheet can be used in place of molybdenum. The insulating properties of the all-metal design come mostly from the gaps between the layers of sheet metal. These gaps prevent heat from being conducted outward from the hot zone. The reflectivity of the inner molybdenum sheet also helps to direct the radiant heat from the elements inward toward the load. All-metal hot zones tend to be preferred when high-vacuum or very clean processing environments are required (medical-component processing). Care must be taken in operating furnaces with all-metal hot zones because molybdenum embrittles due to recrystallization after a single exposure to temperatures above about 1150°C (2100°F). Embrittled heat shields can be relatively easily damaged if struck by fixtures or parts. Due to the high cost of molybdenum, all-metal hot zones also tend to be more expensive than some other choices.

Another popular heat-shield design incorporates graphite-based materials. A standard graphite insulation package normally consists of a minimum thickness of 1.5 inches of graphite-based material in the form of layers of blanket or board. An inner face of graphite foil or foil-bonded carbon composite is added to enhance reflectivity. Because the insulating material is itself porous and permeable, no spaces are required between the layers. These graphite-based materials have excellent insulating properties, are usually cheaper than metal heat shielding and are very easy to work with. Graphite blanket has some advantages over graphite board in terms of construction cost, durability and ease of maintenance.

New Hot-Zone Design

Through production experience, the manufacturer had determined that all-metal insulation does not stand up well in aggressive brazing environments. As condensed metallic constituents from the brazing filler metal build up, the metal insulation begins to curl and crack due to differential expansion between the insulation and the deposit from the filler metal. This eventually causes a deterioration of the hot zone’s insulating properties. Metal insulation is also particularly vulnerable to braze-alloy spillage. Molten braze alloy will often dissolve metal shielding, leaving holes through which heat can escape. The use of thicker sheet and special molybdenum alloys in the insulation will extend the life of an all-metal hot zone but also add considerable expense.

As a manufacturer and user of vacuum furnaces, VAC AERO needed a hot zone designed to withstand aggressive brazing applications and therefore decided to evaluate the performance of graphite-based insulation and heating elements. Tests confirmed that a properly maintained hot zone incorporating these materials can be used to successfully and consistently join difficult-to-braze materials such as nickel-based superalloys. Indeed, the results were better than anticipated. The hot-zone insulation consisted of three layers of graphite blanket with an inner face of foil-bonded carbon composite. While there is little doubt that graphite insulation is more likely to absorb moisture than metal insulation, regular burn-out cycles will rid the insulation of moisture and contaminants that are detrimental to the brazing process. The heating elements were lightweight, curved graphite. http://www.hscf-group.com/

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文章：10

积分：12

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发表于 2012/11/19 11:18:52	第 2 楼

New carbon-carbon composite breaks through the cost barrier

New carbon-carbon composite breaks through the cost barrier

New carbon-carbon composite breaks through the cost barrier

Although widely used for aircraft and F1 brakes because of their lightness and energy absorption, carbon-carbon composites are currently extremely expensive due to the time spent making them. However, a new wet processing method developed by Freno Huntercombe allows them to be produced in a fraction of the time.

The current method of making carbon-carbon composites is to react a carbon fibre pre-form with a mixture of gases in a furnace, thus depositing carbon in the interstices. Since this normally takes between 500 and 800 hours, the resulting material is very expensive.

While F1 cars usually use a new set of brake linings for each race, aircraft brakes have to endure 2000 to 4000 landings. An Airbus A380 has 16 sets of brakes at a cost of approximately ￡20,000 to ￡30,000 per brake, making them a major cost item. According to Boeing, use of carbon-carbon composite brakes enables weight savings relative to steel brakes that range from 250kg on a Boeing 737-600 or 700 to 443 kg on a MD-10 freighter. Naturally, this allows more passengers and/or freight to be carried or fuel consumption to be reduced.

The breakthrough achieved by Freno Huntercombe is the development of a process in which the carbon fibre pre-form is infiltrated by carbon nanoparticles in a water-based suspension. These are followed by ceramic particles that are then reacted to produce a phosphate ceramic. This takes 20 to 30 minutes, meaning composite brakes can be produced at a similar cost to cast iron and steel equivalents.

The compressive strength of the material, according to research director Dr John White, is 100 to 120MPa, which is about the same as that of carbon-carbon fibre composite brakes made by the chemical vapour deposition route. However, as managing director Martin Murphy points out: "Unlike F1 brakes, because ours is a ceramic, wear is low and cold and wet performance is excellent." http://www.hscf-group.com/ProductView.asp?ID=33

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文章：10

积分：12

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发表于 2012/11/19 11:21:07	第 3 楼

Enhanced performance of a Bi-modified graphite felt

Enhanced performance of a Bi-modified graphite felt

Enhanced performance of a Bi-modified graphite felt

Abstract

graphite felt modified with nanodispersed bismuth was studied as electrode in the positive half-cell of a vanadium redox flow battery (VRFB). The felt was easily modified by immersion in a Bi2O3 solution followed by thermal reduction at 450 °C in air. Despite the low metal content (1 at.%) on the surface of the fibers, the Bi-modified felt showed an excellent electrochemical performance (at 1 mV s? 1) in terms of anodic and cathodic peak current densities (21 and 17 mA cm–2, respectively), reversibility (ΔEp = 0.050 V) and overpotential for the V(IV)/V(V) redox reactions. Furthermore, repetitive cyclic voltammetry measurements, at various scan rates, evidenced the long term stability of this material. These results demonstrate that bismuth nanoparticles on the carbon surface act as stable active sites to promote these reactions, and represent a significant step forward towards the development of outstanding electrode materials for VRFB.

Highlights

Bi-modified graphite felt as positive electrode in vanadium redox flow battery. Low Bi content (1%) significantly enhances the electrochemical performance. High peak current densities, reversibility condition and low reaction overpotential. Bi nanoparticles are excellent active sites to promote the vanadium redox reactions. http://www.hscf-group.com/

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文章：10

积分：12

来自:[220.179.xxx.xxx]

发表于 2012/11/19 11:23:40	第 4 楼

How to Read an ac dc adapter

How to Read an ac dc adapter

How to Read an ac dc adapter

Knowing how to read an AC DC adapter is a skill that comes in handy during a variety of home projects. You can easily match power cords to devices by comparing voltage and polarity, and if an adapter is damaged you can use the information to find a replacement

Instructions

1 Identify the voltage. Next to the word "output", you ll see a number with a "V" after it (such as 12V). This is your voltage.

Identify the amperage. After the volts, there will be another number with "A" or "mA" after it (such as 3A or 500mA).

3 Find the diagram that shows three circles connected by lines. The center circle will be open on one side. Whichever sign it opens to is the polarity of the tip. If the circle opens to the plus sign, it is tip positive. If it opens to the minus, sign it is tip negative.

4 If possible, compare the information from the ac dc adapter to the device it powers.

5 Check the Input section to determine the voltage it requires from the wall outlet. A rating between 100 and 120 volts denotes standard voltage used in the United States. A rating of 200 to 240 volts denotes voltage used in a foreign country, and the adapter will require a voltage converter to work in the United States. http://www.gme.com.tw/

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文章：10

积分：12

来自:[220.179.xxx.xxx]

发表于 2012/11/19 11:25:33	第 5 楼

Wooden Blinds Vs

Wooden Blinds Vs

Wooden Blinds Vs

Style

blind manufacturers. You can find an abundance of stains and painted finishes to complement your room s decor, based on the type of wood blind you choose. Custom head rails and cornices can be purchased separately, if the blind does not come with an appealing head rail. Most companies offer color matching for optional cornices and head rails so the color harmonizes with or closely resembles the blind. Aluminum blinds come in many different styles and colors, as well as finishes. You can choose from neutral tones with a flat finish or bright-colored blinds with a glossy finish, and any combination thereof. Each aluminum blind has its own built-in head rail, offering a designer look.

Privacy and Light Blockage

Wooden blinds offer an exceptional privacy option versus many other types of blinds. The solid makeup of the wood prevents individuals from even seeing shapes or shadows through the window. Wood blinds do a fair job of blocking light; however, many specialty blind companies offer a no-holes option. No-holes wood blinds, also referred to as routless blinds, have tiny notches on each side of the slat that sits in the blind ladders. When closed, the notches fit flatly against the ladders, preventing any light from breaking through. Aluminum blinds provide some privacy when closed, but may show shadows and silhouettes within a lighted room. Many aluminum blind manufacturers also offer a no-holes feature with the ladder holes located at the top of the blind slat. When the blinds are closed, the bottom of each slat covers the holes of the slat below it, blocking light from the room. http://www.abcblinds.com.tw/

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文章：10

积分：12

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发表于 2012/11/19 11:29:15	第 6 楼

Fluke T5-1000

Fluke T5-1000

Fluke T5-1000

Product Features

Bandwidth:66Hz

Safety category:UL, CSA, CE, VDE

Voltage measuring ranges, AC:690V

Voltage measuring ranges, DC:6,12,24,50,110,240,415,660

Covered by a two year warranty.

Product Desc ription

From the Manufacturer

Fluke Corporation is the world leader in the manufacture, distribution and service of electronic test tools and software. Since its founding in 1948, Fluke has helped define and grow a unique technology market, providing testing and troubleshooting capabilities that have grown to mission critical status in manufacturing and service industries. From industrial electronic installation, maintenance and service, to precision measurement and quality control, Fluke tools help keep business and industry around the globe up and running. The fluke t5-1000 electrical testers let you check voltage, continuity and current with one compact tool. With the T5, all you have to do is select volts, ohms, or current and the tester does the rest. The open jaw current lets you check current up to 100 amps without breaking the circuit. Its tough test leads stow neatly in the back of the tester, making it easy to tote the T5 in your tool pouch. Detachable SlimReach test probes are customized for national electrical standards. The test leads accept optional accessories such as clips and specialty probes. The T5 has a bandwidth of 66 Hz, a voltage measuring ranges of AC 690 volts and DC 6, 12, 24, 50, 110, 240, 415, and 660 volts. The kit includes the fluke t5-1000 voltage test meter and the H5 electrical tester holder. The T5 meets safety category: UL, CSA, CE, VDE. The T5-1000 electrical test kit is sold one set per package, and is covered by a two year warranty.

Product Desc ription

FLUT5-1000 Features: -Electrical tester with OpenJaw? current.-The T5 electrical tester lets you check voltage, continuity and current with one compact tool.-All you have to do is select volts, ohms, or current and the tester does the rest.-OpenJaw? current lets you check current up to 100A - without breaking the current.-Its tough test leads stow neatly in the back of the tester, making it easy to tote the T5 in your tool pouch Detachable SlimReach? test probes are customized for national electrical standards. The test leads accept optional accessories such a clips and specialty probes. . Specifications: -1000 Voltage, Continuity and Current Tester. Warranty: -30 day warranty on material and workmanship. http://www.rigoloscilloscope.co.uk/wholesale/New-Fluke-T5-1000-Continuity-and-Current-Tester-252.html

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文章：10

积分：12

来自:[220.179.xxx.xxx]

发表于 2012/11/19 11:31:22	第 7 楼

The Lithium Battery Recycling Challenge

The Lithium Battery Recycling Challenge

Growing popularity of hybrid cars is driving the global demand for lithium battery but what about when these cars reach the end of their lives? Can Li-ion batteries be easily recycled? Aswin Kumar looks at the economics of recycling and current trials that are underway.

Increasing oil prices, demand for urban vehicles, megacities and focus on sustainable transportation have kickstarted a substantial trend towards automotive electrification such as hybrids and electric vehicles (EVs). Estimates suggest that by 2020, EVs are likely to account for more than 7% of the global transportation market. However, concerns remain regarding the supply of critical elements needed for these vehicles batteries; there is a threat regarding the availability of Lithium needed for battery production. This threat has shifted the focus towards ensuring the continuous supply of materials needed for the green revolution through reuse and recycling of batteries. With more than 70% of EVs likely to be introduced in 2015 with lithium-ion (Li-ion) based battery chemistry, the recycling of Li-ion has become a crucial topic in the automotive industry.

Lithium supply and challenges

There are a number of challenges that are likely to impact lithium lithium battery supply in the future. Although there is sufficient amount of lithium resources available globally to meet the demand, almost 70% of the global lithium deposits are concentrated in South America s ABC (Argentina, Bolivia and Chile) region. This poses an inherent risk due to the accessibility of the raw material that is available only in a specific geography. Unrest or instability of the governments in these regions can greatly affect the supply and have impact on the battery price and in turn, the vehicle cost.

Lithium is also consumed by a number of other applications or sectors like construction, pharmaceuticals, ceramics and glass and so far the consumption by the automotive industry has been only a small fraction. At present, batteries account for only about one quarter of the current lithium consumption, which is expected to reach about 40% by 2020. Lithium constitutes only a small portion of the cost among other raw materials needed for battery manufacturing. However, with more than one million EVs expected by 2015, there will be a significant pressure on lithium suppliers to cater to demand.

To secure lithium resources, inter-governmental as well as OEM–governmental partnerships are being established. Vehicle manufacturers and the national governments are treating lithium as the future energy source and have started forging alliances to safeguard their needs.

Toyota and Magna International - Mitsubishi have forged partnerships with lithium exploration companies and have invested large sums to develop lithium deposits in Argentina to safeguard and secure the lithium resources to fulfil their needs. Japan has forged a partnership with the Bolivian Government, which binds the former to offer comprehensive economic aid in exchange of supplies of lithium and other rare-earth metals from the latter.

Partnerships such as these enable a strong foothold in the supply chain, increase stakeholders and reduce competition with a focus on controlling price fluctuations in the event of significant rise in demand. Lithium prices have nearly tripled over the last 10 years, as illustrated in Figure 1. Agreements are negotiated between seller and the user and the price varies by use in industry/sectors. Current prices are around $5,500 to $6,000 per ton of lithium carbonate depending on applications.http://en.fansobattery.com/
lithium battery
lithium battery
primary lithium battery

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文章：10

积分：12

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发表于 2012/11/19 11:33:58	第 8 楼

FANSO CP9V lithium battery 1200mAh for smoke detectors

FANSO CP9V lithium battery 1200mAh for smoke detectors

FANSO CP9V lithium battery 1200mAh for smoke detectors

SUPPLY PRODUCT FANSO CP9V lithium battery 1200mAh for smoke detectors (1) high energy density up to 420WH/Kg(800WH/dm3).

(2) High operation voltage, 3.3V~3.6V upon loading resistance.

Battery (CP9V)

Excellent performance in extreme temperatures lightweight Lithium technology Made in china, cr Digital camera photo lithium Batteries CR-123A Digital Camera /photo Lithium Batteries, AA AA AAA C, D, 9V, 2CR5, CR123A, CR17335

Nominal capacity:1200mAh

Nominal voltage:9.0V

Max. Constant current2000mA

Workable temperature-40--+60 degrees

"Product Desc ription

(1) high energy density up to 420WH/Kg(800WH/dm3).

(2) High operation voltage, 3.3V~3.6V upon loading resistance.

(3) Long storage life, less than 2% of self-discharging rate per year, could be stored for 10~15 year at room temperature.

(4) Non-magnetic stainless steel case, hermetically sealed.Be safe for transportation and general shock.No leakage problem.http://en.fansobattery.com/cpshow.aspx?id=211

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文章：10

积分：12

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发表于 2012/11/19 11:36:32	第 9 楼

primary lithium battery

primary lithium battery

primary lithium battery find application in many long-life, critical devices, such as artificial pacemakers and other implantable electronic medical devices. These devices use specialized lithium-iodide batteries designed to last 15 or more years. But for other, less critical applications such as in toys, the lithium battery may actually outlast the device. In such cases, an expensive lithium battery may not be cost-effective.

primary lithium battery can be used in place of ordinary alkaline cells in many devices, such as clocks and cameras. Although they are more costly, lithium cells will provide much longer life, thereby minimizing battery replacement. However, attention must be given to the higher voltage developed by the lithium cells before using them as a drop-in replacement in devices that normally use ordinary zinc cells.

primary lithium battery also prove valuable in oceanographic applications. While lithium battery packs are considerably more expensive than standard oceanographic packs, they hold up to three times the capacity of alkaline packs. The high cost of servicing remote oceanographic instrumentation (usually by ships) often justifies this higher cost.

Sizes and formats

See also: Button cell, Battery nomenclature, and List of battery sizes

Small primary lithium battery are very commonly used in small, portable electronic devices, such as PDAs, watches, camcorders, digital cameras, thermometers, calculators, laptop BIOS, communication equipment and remote car locks. They are available in many shapes and sizes, with a common variety being the 3 volt "coin" type manganese variety, typically 20 mm in diameter and 1.6–4 mm thick. The heavy electrical demands of many of these devices make primary lithium battery a particularly attractive option. In particular, primary lithium battery can easily support the brief, heavy current demands of devices such as digital cameras, and they maintain a higher voltage for a longer period than alkaline cells.http://en.fansobattery.com/

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文章：10

积分：12

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发表于 2012/11/19 11:39:04	第 10 楼

Hacking the Rigol DS1052E Oscilloscope with Linux

Hacking the Rigol DS1052E Oscilloscope with Linux

Hacking the Rigol DS1052E Oscilloscope with Linux

I was in the market for an oscilloscope, but I didn t want to spend much. I found out about Rigol and their line of $300-400 scopes, and was getting ready to buy one. Then I found a post on how to make your ds1052e, which costs about $400 into a DS1102E, which costs about $700 with a simple firmware modification! I bought the scope right after, and I received it in the mail today. It s pretty nice by default, but doubling the bandwidth is always a plus.

The ds1052e has a 50Mhz maximum frequency, but it has exactly the same hardware (as far as the reverse-engineering folks can tell) as the DS1102E, which has a 100Mhz maximum. This guide will show you how to make the switch very easily using Linux. You can do it in Windows too, but it s a bit more involved, and Linux makes it really really easy.

I ve attached the Rigol user guide for both units, in case you don t have one. http://www.rigoloscilloscope.co.uk/wholesale/Rigol-Oscilloscope-50MHz-DS1052E-1G-SG-1M-3-years-warranty-Special-Offer-24.html

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