During the probe it was found that a little figure of companies have established a chokehold on the magnetic levitation train industry. Some of these companies have been researching magnetic levitation trains and the subsequent superconductor engineering for about 50 old ages. As their research is so far in front and the rational belongings rights on the engineering, means a company diversifying into maglev engineering is far behind and impossible to vie at this minute in clip. Several old ages of research would be needed in order to vie. However two ceramics were identified that could be get downing points for farther research. These are YBCO and BSCCO. These ceramic superconductors can both be cooled by liquid N which is abundant, cheap, easy to hive away and easy to utilize. This is a major benefit, in both financially and practically. Out of these two it was decided that BSCCO was the better and is what is recommended to continue with.
The methods of processing are more varied and sol-gel processing, high energy pulverization compression techniques and seeded infiltration growing technique ( SIG ) were all analysed. From the research that was conducted the best method to continue with would be the seeded infiltration growing technique ( SIG ) . This was due to its ability to forestall macro defects and besides produce big merchandises with few deformations.
Superconductivity, which occurs in certain stuffs at really low temperatures, means the stuff has no electrical opposition and no interior magnetic field when superconductive. In 1911, it was discovered by Heike Kamerlingh Onnes [ 1 ] that the electrical opposition of quicksilver disappeared perfectly when cooled down to 4.2 Kelvin utilizing liquid He. The phenomenon is so called superconductivity, while the other important characteristic, diamagnetism, was discovered by Meissner and Ochsenfeld in 1933 [ 1 ] . They found if a superconductor was cooled in a magnetic field, the magnetic initiation lines were expelled at the same clip when the electrical opposition disappeared. Although the job of magnetoelectricity was overcome, the barrier from the low critical temperatures remained hard to interrupt.
In the early times, with regard to superconductors, most focal points were on simple elements like Sn and aluminum, assorted metallic metals and some heavily-doped semiconducting materials [ 2 ] . However, the border of the long-run deficiency of advancement in superconductor research was broken in 1986, when some cuprate-perovskite ceramic stuffs were found with critical temperatures of more than 90 Kelvin. From a practical position, 90 Kelvin is easy to make with the readily available liquid N ( boiling point 77 Kelvin ) . This means more experimentation and more commercial applications are executable, particularly if stuffs with even higher critical temperatures could be discovered [ 2 ] .
With the development of superconducting ceramics, more and more attendings were paid to their attractive applications in power coevals, power transmittal and energy storage. What ‘s the most attention-getting in recent decennaries ; superconducting ceramics are playing an of import function in magnetically levitated trains.
Based on the different engineerings used, levitation systems can be classified as Electro Magnetic System ( EMS ) and Electro Dynamic System ( DMS ) [ 3 ] . Due to the diamagnetism of superconductors, they can be used in the DMS. When a superconductor is positioned above a lasting magnet, repulsive force will look between them since no magnetic force is able to travel through the superconductor. Hence the levitation brought by the repulsive force consequences in a high velocity of about 500 kilometers per hours, which the magnetically levitated trains can accomplish without any opposition from touching the land.
Equally early as 1922, Hermann Kemper, a German applied scientist, set frontward the rule of electro-magnetic levitation, and in 1934 he succeeded in using for a patent of magnetic levitation trains. It was the first beginning of the magnetic levitation trains. Since 1970s, with the development of the economic strength of the universe ‘s industrialised states, the developed states, such as Germany, Japan, the United States, Canada, France, Britain, have begun to explicate programs for magnetic levitation transit system development to heighten the transit capacity to run into the demands of their farther
However, the United States and the former Soviet Union gave up the research in 1970s and 1980s, severally. Presently, merely a few states, including German, Britain, Japan and China are still analyzing the magnetic levitation system, and fortuitously, amazing advancement has been achieved, particularly with the usage of the superconducting ceramics.
A magnetic levitation train system was laid in Berlin, Germany, in the 1980s. There were three Stationss in the system, the length of which was 1.6km, utilizing a driverless train. However, due to some political grounds, the line was changed to a general wheel-rail one after running two months, when the Berlin Wall fell.
Another low-speed magnetic levitation train was used in Birmingham International Airport in Britain, from 1984 to 1995. But the dependability jobs made the line changed later.
The magnetic levitation train in Shanghai, China, is shown in Figure 1. It is running presents, with a length of 30km, and the clip required to travel through is merely 8 proceedingss. However, due to the really high cost, the train is merely a engineering merchandise, alternatively of a agency of transit.
Fig. 1 Maglev levitation train in Shanghai, China
Doubtless, the rapid-developing society calls for high-speed, comfy and low energy cost transit like magnetically levitated trains. On the other manus, the development of magnetically levitated trains can non populate without superconducting ceramics for its possibility to transport out high critical temperature, low cost and feasibleness.
At the minute there are merely a few Maglev systems which are used commercially such as the Shanghai Maglev Train which started building in April 2001 and finished in 2004 [ 4 ] . Another is the Limino line in Japan which is a 9 station line in Aichi and opened in 2005. Although this has been really successful few other Maglev trains are presently unfastened to the populace. There was a Maglev train which served between Birmingham International Airport and Birmingham International Railway Station but this installation closed in 1995 due to expensive fixs. This was replaced with a coach service and so by an AirRail Link.
There are nevertheless a big figure of proving installations which have been to a great extent invested in to seek and acquire the engineering used more world-wide but due to expensive start up costs few states have decided to continue with Maglev and alternatively remain with the traditional Railway systems. The most known of these trial installations is the Transrapid trial installation in Emsland, Germany which has a 31.5km length path which opened in 1984. Another good known trial installation is the JR-Maglev trial installation in Yamanashi Prefecture, Japan where the universe record for the fastest Train was recorded at traveling 581km per hr on December 2nd 2003 [ 5 ] .
Although the engineering proves that the going times will be greatly reduced there has been small involvement in upgrading to a magnetic levitation system. A good illustration of this would be the UK Ultraspeed undertaking associating London to Glasgow. This undertaking would hold cut the clip taken on most journeys in half but the undertaking was rejected by the authorities as it was excessively dearly-won. Although this was non successful at that place are other undertakings planned which are likely to travel in front. There are 2 possible undertakings in Australia ( Melbourne and Sydney ) , a figure in the United States, an extension of the Shanghai Maglev Train, a nexus between Munich and its airdrome, a twosome of possible undertakings in India and a line between Tokyo and Nagoya projected to get down in 2025. Not all of these are likely to travel in front though as the programs are merely merely get downing for these undertakings. However it does demo that the market size for Maglev is turning although it is unsure what rate it will increase at. It besides has to be said that the size of the current market is really little and there has already been a big sum of research conducted around the development of Maglev.
At the minute there are two chief contractors sing the development of Maglev trains these are Transrapid, a German company based in Emsland which have been developing Maglev trains since the late 1960 ‘s. it is a joint venture by Siemens and ThyssenKrupp. Another chief developer is a joint venture by Central Japan Railway Company and Railway Technical Research Institute which is based in Japan and has the universe record for the fastest train. They have 5 proving installations located across Japan and have been developing the system longer than Transrapid as they started in 1962, 7 old ages earlier.
Superconductivity is when 0 electrical opposition is observed. The passage temperature at which the opposition becomes zero is known as the critical temperature.
Different stuffs reach this critical temperature at different temperatures. The first superconductor to be discovered was high pureness quicksilver cooled by liquid He. It has an highly low critical temperature and liquid He was non readily available and highly expensive therefore the commercial application of superconductivity was non executable. The optimal critical temperature is above room temperature, so its optimal on the job conditions would be room temperature and chilling of the superconductor would be unneeded.
To get the better of the job of holding to chill the superconductors to highly low temperatures, other superconductors would hold to be discovered. These new superconductors must hold a high critical temperature.
In 1987 a superconductor was discovered, this new superconductor was Yttrium Barium Copper Oxide. It was a superconductor that could be cooled with liquid N instead than liquid He. This was a discovery as liquid N is comparatively inexpensive. This meant superconductivity engineering could go more readily available.
Since so the critical temperature of ceramic superconductors have increased dramatically. The universe record for critical temperature is now about 254 K. The power of the superconductive magnets have besides increased dramatically. The universe record is now 26.8 tesla.
Figure 2 is a timeline picturing the find of early superconductors.
The most effectual superconductors for magnetic levitation trains are type II superconductors. They normally conduct at higher temperatures than type I superconductors. This means they conduct high currents and can therefore do more effectual electromagnets.
Yttrium Barium Copper Oxide
One high temperature type II superconductor is Yttrium Barium Copper Oxide besides known as YBCO ( with a chemical expression of YBaa‚‚Cua‚?Oa‚‡ ) . YBCO was the first stuff to go a superconductor over 77k, the boiling point of N. Although it has a high critical temperature, YBCO is non used extensively in magnetic levitation engineering because although individual crystals of YBCO have a high critical current denseness, polycrystals have a low critical current denseness. This means merely a little current can be transferred while still being superconductive. This job is due to crystal grain boundaries in the YBCO.
Figure 3 shows the construction of YBaa‚‚Cua‚?Oa‚‡
Bismuth Strontium Calcium Copper Oxide
Another high temperature superconductor is Bismuth Strontium Calcium Copper Oxide besides known as BSCCO. It is a cuprate superconductor that has a critical temperature which is above the boiling point of liquid N. BSCCO needs to hold an surplus of O atoms in order to superconduct.
BSCCO was the first superconductor to be used for superconducting wires. It has the same jobs with grain boundaries as YBCO, nevertheless these can be overcome thanks to Van der Waals coupled BiO beds. BSCCO can besides be made into wires by the pulverization in tubing procedure.
The construction of BSCCO-2212 is shown in Figure 4.
Over the last 20 old ages ceramic superconductors have become the drastically more effectual in their usage in magnetic levitation trains, nevertheless the individuality of specific ceramics is kept secret by the research companies so they keep their competitory advantage. Superconductors such as ( Tla‚„Ba ) Baa‚‚Caa‚‚Cua‚‡Oa‚?a‚? in a 9223 construction have a really high critical temperature but are non suited to be used in the magnetic levitation train industry yet.
Both YBCO and BSCCO could be used as superconductors for magnetic levitation trains nevertheless if selected they would non be every bit effectual as the superconductors used by companies such as Transrapid. As companies like this have been developing superconductors for many old ages their engineering is really advanced and besides secret.
In conventional paths, like other ceramic stuffs, there are three phases to treat a superconducting ceramic used in magnetic levitation trains: pulverization commixture, determining and green organic structure fire. However, since superconducting ceramics are a little more complicated, the stuff should be synthesized before blending. Furthermore, to obtain a green goods a merchandise which can be used in magnetic levitation trains, constituents patterning and fabrication is indispensable after all the processing phases mentioned above. The concrete phases are shown in Figure 5.
Synthesis of pulverizations
Components patterning and fabrication
Fig. 5 Processing of superconducting ceramic merchandises
Among these phases, pulverization synthesis and pulverization compression are the cardinal issues of fabricating an ideal superconducting ceramic.
Powder synthesis -sol-gel processing
When sing how to synthesize superconducting ceramic pulverizations, normally a simple mixture of all reagent oxides [ 6 ] or a mixture of a precursor stage, a consequence of pre-reacting, with HgO [ 7 ] is produced to respond at a high temperature. High grades of homogenization of the cations are in demand in both instances [ 8 ] .
Presently, sol-gel processing is frequently chosen to synthesize superconducting ceramic pulverizations, for an first-class homogenization at an atomic graduated table of the elements can be achieved.
The basic thought of sol-gel processing is to get down from a cations solution, and so to jellify it by polymerization [ 9 ] . It consequences in some gel which can be manipulated easy. After that, a xerogel is obtained by heating.
Obviously, the advantages, such as chemical homogeneousness and chemical responsiveness, have made sol-gel one of the most ideal ways to obtain optimal superconducting ceramics. However, at one clip sol-gel processing was merely used to synthesize Ba-Ca-Cu-O precursor pulverizations, because the temperature required to transform the gel into the oxide stage is higher than the decomposition temperature of HgO [ 10 ] .
As a effect, an improved sol-gel method is developed to synthesize some complex oxides [ 11 ] and YBa2Cu3O7 in peculiar [ 12 ] . Unlike the conventional sol-gel, which includes hydrolysis-condensation of inorganic precursors, the new path uses the jellification of a solution by an unmoved polymerization of acrylamide monomers. It gives possibility to bring forth a big sum of pulverization in a much shorter clip.
In decision, the improved sol-gel method has a clear advantage of quality compared with the solid province reaction, and advantages of processing clip and wider pertinence compared with the conventional sol-gel path. That is the ground why today sol-gel processing is so widely used in superconductor industry.
Powder compression -high energy pulverization compression techniques
The end of pulverization compression is to bring forth a green organic structure which is as dense and Se strong as possible. Presents, to manufacture a superconductor merchandise, dynamic compression is preferred for its really short continuance of the procedure and the development of high force per unit areas compared with the conventional compression techniques [ 13 ] .
In the present work, there are two high energy pulverization compression techniques normally employed for bring forthing superconducting YBCO ceramics: explosive compression and electromagnetic compression.
The explosive compression and the electromagnetic compression are shown in Figure 6 ( a ) and ( B ) , severally. While the explosive compression creates high daze force per unit areas and high temperatures to fracture the original grains and sinter, with the shock-waves originated from explosive explosion and propagated through the porous media, the electromagnetic compression uses the consequence of a high strength transeunt magnetic field.
( a ) ( B )
Fig. 6 Conventional diagrams of:
explosive compression ;
( 1: Ag tubing ( ?12/10 ) ; 2: YBCO pulverization ; 3: Ag pulverization ; 4: plastic phonograph record ; 5: steel bolt MS ; T: selenoid ; C: capacitance ; 5: switch. ) [ 13 ]
In merchandises manufactured with high energy pulverization compression techniques, a decrease in porousness is found as a consequence of the really short continuance of the procedure and the development of high force per unit areas. At the same clip during the compression procedure, break of the initial grains and formation of new grain boundaries lead to an addition in inter-grain current conveyance in the superconducting province.
A fresh processing path -seeded infiltration growing technique ( SIG )
As a novel treating path with infinite potency for bring forthing superconducting ceramics in the hereafter, seeded infiltration growing technique ( SIG ) has been used to treat mono-domain YBa2Cu3O7?x ( Y123 ) majority superconductors. It includes the combination of thaw infiltrated liquid beginning ( Ba3Cu5O8 ) into the Y2BaCuO5 ( Y211 ) pre-form and the nucleation of Y123 sphere from SmBa2Cu3O7 crystal seed [ 14 ] .
The full infiltration of the Y211 pre-form by liquid stage is shown in Figure 7. By and large, the rule is to optimise the sum of liquid stage in order to sooner change over Y211 into Y123 by doing the Y211 pre-form absorb more liquid.
Fig. 7 Configuration of SIG procedure [ 14 ]
In the SIG procedure, the liquefied liquid stage can infiltrate into the unfastened porous Y211 block, ensuing in a big lessening in the macro defects and porousnesss in the sample, whilst the sample shrinking can be neglected. With regard to dense textured samples, the SIG procedure could be taken into history with high Jc values [ 15 ] .
Materials and processing
From the stuffs and the processing subdivision a figure of different ceramics and treating methods have been identified. In this subdivision we will place which procedure and which ceramic the company should continue with. First the ceramic will be discussed.
The two types of ceramic that are discussed are Yttrium Barium Copper Oxide and Bismuth Strontium Calcium Copper Oxide. From the information in the earlier subdivision we can see that both these ceramics are equal for a superconductor and are both really similar. However in Yttrium Barium Copper Oxide the polycrystals have a low critical current denseness significance at that place can merely be a little current whilst it is superconducting. Although the same job occurs in Bismuth Strontium Calcium Copper Oxide it can be overcome with Van der Waals coupled BiO beds. Therefore the ceramic top usage is Bismuth Strontium Calcium Copper Oxide.
The ways of treating the ceramic are more complex. The methods listed earlier are ; sol-gel processing, high energy pulverization compression techniques and seeded infiltration growing technique ( SIG ) . First the sol-gel procedure will be discussed. During this a good chemical homogeneousness and chemical responsiveness are achieved which are greatly desired in superconductors. This is why this procedure is presently widely used to bring forth superconductors.
The 2nd method is high energy pulverization compression techniques. During this there is frequently a decrease in porousness compared with other procedures due to the short clip it takes to bring forth the merchandise and the high force per unit areas they are put under. This besides leads to a break of the original grain boundaries and the formation of which causes an addition in the inter-grain current conveyance during the superconducting province.
The concluding method is SIG. this is a comparatively new method of treating ceramics which is presently used to bring forth bulk superconductors. This procedure allows the ceramic to hold less macro defects and porousnesss in the sample and cut down the shrinking of the ceramic. One of the important advantages of the SIG procedure that it offers the flexibleness to engineer belongingss, and to bring forth big specimens of near-net form without deformations makes it one of the most promising processing path to fabricate a superconducting ceramic used in magnetic levitation trains in the hereafter.
From the points above it has been decided to continue with the SIG method as it is seen as a good manner to acquire the best belongingss out of the ceramic and is a different method to conventional ways of treating superconductors perchance giving us an border over the rivals.
Recommended class of action
The most outstanding job with Magnetic levitation trains is the immense sum of capital needed to finance such an ambitious venture. There have been several different paths explored seeking to refer the most efficient and cost effectual with changing degrees of success. Although landmarks have been reached such as the JR-Maglev train, the fastest rail vehicle in the universe. This train reached a top velocity of 381 kilometers per hours ( 361 miles per hour ) utilizing an Electro-dynamic Suspension system. There are several bing magnetic levitation systems some of them including the distance have been naming below and where available the cost of the system:
General Atomics, San Diego. 120 meter trial path. $ 90 million in research support from the federal authorities, entire cost terra incognita.
Transrapid, Emsland, Germany. 31.5 km path.
JR-Maglev, Yamanashi, Japan. 18.4 km path.
Linimo, Aichi, Japan. 8.9 km path, approximately $ 100 million per kilometer.
Shanghai Maglev, China. 30.5 km path, $ 1.33 billion.
There have besides been maglev systems proposed in Australia, UK, Iran, Japan, Venezuela, China, India, the US, Germany and Indonesia. However several of these planned systems have been abandoned such as the London-Glasgow line.The pecuniary job is hence non merely linked to technological jobs such as holding to construct new paths but besides a limited possible mark market. However the limited mark market is linked to the high cost of magnetic levitation trains, with research this cost should cut down and therefore the figure of possible investors should increase. This is bad and a high hazard venture as technological discoveries might non be reached.
Research into maglev train systems have been afoot since the 1970s. A little figure of companies have established a chokehold on magnetic levitation engineering and the constitutional superconductor engineering and production. Their current engineering is really close and if Rennib Advanced Ceramics Ltd were to get down developing superconductors, the engineering would be several old ages behind market leaders such as Transrapid. Having said this, competition is one of the chief factors that defines capitalist economy, with competition the monetary value of magnetic levitation engineering would diminish, therefore the market would increase as maglev systems would be more low-cost, and with a larger market becomes more possible net income.
One manner for the magnetic levitation market to spread out is to evacuated tunnels. This means the trains would run in a vacuity with a pressurised cabin. As it would be a vacuity there would be no air opposition intending the theoretical velocities would be faster than an airplane. However this system would increase the cost even further and there is important safety hazard refering the deficiency of O.
In its current state of affairs magnetic levitation rail systems have a limited possible mark market, highly high costs with a little figure of companies with a chokehold on this niche market. As Rennib Advanced Ceramics is a late starting motor to the magnetic levitation market and with the limited possible growing of the market unless immense sums of capital are invested, superconductors for magnetically levitated trains would non be a wise investing.
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