CN1515372A - Preparation method of Al2O3-MgO-ZrO2 ladle air plug - Google Patents
Preparation method of Al2O3-MgO-ZrO2 ladle air plug Download PDFInfo
- Publication number
- CN1515372A CN1515372A CNA031184227A CN03118422A CN1515372A CN 1515372 A CN1515372 A CN 1515372A CN A031184227 A CNA031184227 A CN A031184227A CN 03118422 A CN03118422 A CN 03118422A CN 1515372 A CN1515372 A CN 1515372A
- Authority
- CN
- China
- Prior art keywords
- mgo
- preparation
- content
- porous plug
- alumina
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Landscapes
- Treatment Of Steel In Its Molten State (AREA)
- Compositions Of Oxide Ceramics (AREA)
Abstract
The present invention belongs to the field of refractory material by using alumina as base material. Its technical scheme is as follows: it is formed from plate corundum whose Al2O3 content is greater than or equal to 99.4%, zirconium corundum whose zirconium oxide content is 5-30%, electrofused magnesium sand whose MgO content is greater than or equal to 96%, high-aluminium micropowder whose Al2O3 content is greater than or equal to 99.4%, dispersion alumina whose Al2O3 content is greater than or equal to 75%, special adhesive and organic fibre. The above-mentioned materials are stirred with water, poured, dried and fired so as to obtain the invented product. It has high durability, good thermal-shock resistance, slag corrosion resistance and molten steel scouring abrasion resistance.
Description
One, technical field
The invention belongs to the aluminium oxide is the fire resisting material field of base-material, relates in particular to a kind of preparation method who is used for the ladle porous plug.
Two, background technology
By the porous plug Argon in molten steel that is installed in ladle bottom stir, evenly composition and temperature, quicken the carrying out of various chemical reactions in the smelting process, reduce sulphur, phosphorus, oxide and other impurity in the molten steel, molten steel is played catharsis.
In the selection of porous plug material, generally popular is magnesia and corundum two classes both at home and abroad.In use, because of periclase and wustite (FeO) formation continuous solid solution, so magnesia porous plug has good repellence to the basic slag that contains iron oxide and calcium oxide, but magnesia thermal coefficient of expansion is big, elastic modelling quantity is high, thermal shock resistance is poor, and slag permeates to the periclase intercrystalline in use, and then causes its structure spalling.By contrast, corundum matter porous plug has characteristics such as good high-temperature performance and anti-thermal shock stability, but pure corundum matter porous plug in use erosion-resisting characteristics is poor, flake-off piece phenomenon is serious.
For further improving corundum porous plug anti-scour property, adopt added Cr more in matrix
2O
3The micro mist measure.The employing electro-corundum is primary raw material, adds simultaneously Cr
2O
3The micro mist sintering is made (ZL95110026.2), Cr
2O
3Form the aluminium chromium solid solution with corundum fine powder, then form the glassy phase that contains chromium with other impurity, be the filling of isolated island shape between the pink fused alumina crystal, this full-bodied chromium glass that contains stops the infiltration of slag highly beneficial relatively, but too fine and close institutional framework makes its thermal shock resistance deterioration, and Cr
2O
3At high temperature volatile, harmful to environment.
Be the anti-erosion of seeking porous plug and the overall balance of thermal shock resistance, adopted and added spinelle (ZL94118264.9) in the matrix, cooperate SiO
2Raw material (the flat 10-251739 of JP), adding Al
2O
3ZrO
2Be raw material (the flat 10-280029 of JP), add zirconium mullite fine powder (the flat 9-52168 of JP), with Al
2O
3ZrO
2Raw material and MgO micro mist add (the flat 9-268051 of JP) simultaneously, make spinelle, mullite, zirconium mullite consist of the matrix part of porous plug, but mullite, zirconium mullite are easily wetting in molten steel, and corrosion resistance is poor.The bond of these patented technologies generally adopts pure calcium aluminate cement or ultrafine silica powder etc., rely on their hydrations and Coagulating binding, give the porous plug normal temperature strength, and the calcium oxide in the cement easily forms the eutectic point phase with castable or slag under lower temperature, under the prerequisite that exists at silica, CaO-Al
2O
3-SiO
2The ternary system lowest total of the melting point only has 1170 ℃.The existence of liquid phase, the high-temperature behavior of deterioration porous plug greatly, thus influence the raising of its durability.
Three, summary of the invention
Task of the present invention provides a kind ofly can improve durability, environmentally safe, good thermal shock resistance is arranged, the porous plug preparation method of erosion resisting and high temperature resistance mechanical erosion performance.
For realizing above-mentioned task, the technical solution adopted in the present invention is: it is made up of plate diamond spar, fused alumina zirconia, fused magnesite, high alumina matter micro mist, dispersed aluminium oxide, special combination agent, organic fiber.
Wherein, the Al of plate diamond spar
2O
3Content 〉=99.4%, the zirconia content of fused alumina zirconia are 5～30%, the MgO content of fused magnesite 〉=96%, the Al of High-Alumina micro mist
2O
3Content 〉=99.4%, the Al of dispersed aluminium oxide
2O
3Content 〉=75%.
The weight ratio of said components: plate diamond spar is 70～80%, and fused alumina zirconia is 5～25%, and fused magnesite is 0.5～10%, high alumina matter micro mist is 3～15%, dispersed aluminium oxide is 0.5～1.5%, and the special combination agent is 2～5%, and organic fiber is 0.06% (adding).
The grain composition of said components: plate diamond spar is 6～0mm, and fused alumina zirconia is 1～0mm, and fused magnesite is 1～0mm, and high alumina matter micro mist is 0.045～0mm, and dispersed aluminium oxide is 0.045～0mm, and the special combination agent is 5～0 μ m.
The special combination agent can be selected Alphabond, ρ-Al
2O
3, one or more combination in the alumina gel powder, magnalium gel powder.
Add 4.4～5% water by the mixture of said ratio, stir pourable moulding after 6 minutes (but the activity duration is 50～60min), through 110 ℃ * 24h drying, 1600 ℃ * 5h burns till then.
Fused alumina zirconia raw material and Al
2O
3Relatively, its thermal coefficient of expansion is little, can not produce micro-crack because the two thermal coefficient of expansion does not mate in the use procedure or sintering process of porous plug, and this crackle can absorb the stress that produces and heat-resisting spalling is improved.Simultaneously the MgO in the matrix is when burning till and Al
2O
3The spinelle reaction of formation takes place, and follows appropriate volumetric expansion and dense structure, and ZrO
2Difficult wetting by molten steel and slag, therefore, significantly strengthen resistance to slag corrosion.Replace cement and silicon powder with the special combination agent, water material feeding and be high-intensity being higher than to make under 1000 ℃ the temperature, replace existing pottery combination, greatly reduce even eliminate intercrystalline low melt-phase from combination, improve direct combination degree, thereby strengthened the high temperature resistance mechanical erosion ability of porous plug.
It is primary raw material that the present invention adopts plate diamond spar, cooperates simultaneously fused alumina zirconia and magnesia, selects the special combination agent, forms and the adjustment grain composition Al of manufacturing by feed proportioning optimization
2O
3-MgO-ZrO
2The matter porous plug of steel ladle has high durability and good anti-thermal shock, slag corrosion resistance and the advantages such as anti-molten steel performance of flushing and environmentally safe.Be suitable for bottom ladle, the tundish molten steel Argon being used.
Four, the specific embodiment
Embodiment A l
2O
3-MgO-ZrO
2The preparation method of matter porous plug of steel ladle is that the weight ratio of its component is: Al
2O
3The plate diamond spar of content 〉=99.8% is 74～78%, and zirconia content is that 15～25% fused alumina zirconia is that the fused magnesite of 15～20%, MgO content 〉=98% is 1～1.5%,, Al
2O
3The High-Alumina micro mist of content 〉=99.8% is 7～12%, Al
2O
3The dispersed aluminium oxide of content 〉=75% is 0.5～1%, Al
2O
3The High-Alumina bond Alphabond of content 〉=99.4% is 2～3%, organic fiber 0.06% (adding).
The grain composition of each component: plate diamond spar: 6～0mm, fused alumina zirconia are 1～0mm, and fused magnesite is 1～0mm, and high alumina matter micro mist is 0.045～0mm, and dispersed aluminium oxide is that 0.045～0mm, high alumina matter bond Alphabond are 10～0nm.
Add 4.4% water by the mixture of said ratio, stir after 6 minutes (adopting the jumping table method to measure to water the slamp value after the material feeding vibration 30 times is 162mm) moulding by casting, through 110 ℃ * 24h drying, 1600 ℃ * 5h burns till then.
It surveys physical and chemical index: apparent porosity is 12.9%, 1600 ℃ * 5h of 110 ℃ * 24h 15.5%; Bulk density is 110 ℃ * 24h 3.22g/cm
3, 1600 ℃ * 5h 3.2g/cm
3Compressive resistance is 110 ℃ * 24h 54.9MPa, 1600 ℃ * 5h 106.3MP; Strength at normal temperature is 110 ℃ * 24h5.9MPa, 1600 ℃ * 5h 20MP; The anti-slag of static crucible is 1600 ℃ * 3h, does not have infiltration and erosion substantially; The line rate of change is that 1600 ℃ * 5h burns back 0.11%; Is 64 through 1100 ℃ of water-cooled circulations (being incubated 20 minutes, water-cooled 5 minutes) until the thermal shock number of times of broken end.
Comparative example adopts (in weight ratio): Cr
2O
3Fine powder is 4%, and plate diamond spar is 90.5%, and High-Alumina bond Alphabond is 3%, and fused magnesite is 1.5%, and organic explosion-proof fiber is 0.06% (adding), and dispersed aluminium oxide (contains 80% Al
2O
3) be 1%.
Mixture by said ratio adds 4.4% water, stirs after 4 minutes, and the slamp value that adopts jumping table method mensuration castable to vibrate after 30 times is 146mm, gets final product moulding by casting.It surveys physical and chemical index: apparent porosity is 13.2%, 1600 ℃ * 5h of 110 ℃ * 24h 15.8%; Bulk density is 110 ℃ * 24h 3.23g/cm
3, 1600 ℃ * 5h 3.2g/cm
3Compressive resistance is 110 ℃ * 24h 42.4MPa, 1600 ℃ * 5h84.1MP; Strength at normal temperature is 110 ℃ * 24h 5.1MPa, 1600 ℃ * 5h 18.8MP; The anti-slag of static crucible is 1600 ℃ * 3h, does not have infiltration and erosion substantially; The line rate of change is that 1600 ℃ * 5h burns back 0.024%: is 26 through 1100 ℃ of water-cooled circulations (being incubated 20 minutes, water-cooled 5 minutes) until the thermal shock number of times of broken end.
Claims (7)
1, a kind of Al
2O
3-MgO-ZrO
2The preparation method of matter porous plug of steel ladle is characterized in that being made up of plate diamond spar, fused alumina zirconia, fused magnesite, High-Alumina micro mist, dispersed aluminium oxide, special combination agent, organic fiber.
2, Al according to claim 1
2O
3-MgO-ZrO
2The preparation method of matter porous plug of steel ladle is characterized in that the Al of described plate diamond spar
2O
3Content 〉=99.4%, the zirconia content of fused alumina zirconia are 5～30%, the MgO content of fused magnesite 〉=96%, the Al of High-Alumina micro mist
2O
3Content 〉=99.4%, the Al of dispersed aluminium oxide
2O
3Content 〉=75%.
3, according to each described Al in the claim 1～2
2O
3-MgO-ZrO
2The preparation method of matter porous plug of steel ladle, the weight ratio that it is characterized in that described component: plate diamond spar is 70～80%, fused alumina zirconia is 5～25%, fused magnesite is 0.5～10%, the High-Alumina micro mist is 3～15%, dispersed aluminium oxide is 0.5～1.5%, and the special combination agent is 2～5%, and the organic fiber that adds is 0.06%.
4, according to each described Al in the claim 1～3
2O
3-MgO-ZrO
2The preparation method of matter porous plug of steel ladle is characterized in that grain composition: plate diamond spar is 6～0mm, and fused alumina zirconia is 1～0mm, fused magnesite is 1～0mm, the High-Alumina micro mist is 0.045～0mm, and dispersed aluminium oxide is 0.045～0mm, and the special combination agent is 5～0 μ m.
5, according to each described Al in the claim 1～4
2O
3-MgO-ZrO
2The preparation method of matter porous plug of steel ladle is characterized in that described special combination agent can select Alphabond, ρ-Al
2O
3, one or more combination in the alumina gel powder, magnalium gel powder.
6, according to each described Al in the claim 1～5
2O
3-MgO-ZrO
2The preparation method of matter porous plug of steel ladle is characterized in that adding 4.4～5% water by the mixture of said ratio, stirs pourable moulding after 4 minutes, and through 110 ℃ * 24h drying, 1600 ℃ * 5h burns till then.
7, according to each described Al in the claim 1～6
2O
3-MgO-ZrO
2The porous plug of steel ladle product of preparation method's preparation of matter porous plug of steel ladle.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 03118422 CN1289241C (en) | 2003-01-07 | 2003-01-07 | Preparation method of Al2O3-MgO-ZrO2 ladle air plug |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 03118422 CN1289241C (en) | 2003-01-07 | 2003-01-07 | Preparation method of Al2O3-MgO-ZrO2 ladle air plug |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1515372A true CN1515372A (en) | 2004-07-28 |
| CN1289241C CN1289241C (en) | 2006-12-13 |
Family
ID=34239503
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 03118422 Expired - Fee Related CN1289241C (en) | 2003-01-07 | 2003-01-07 | Preparation method of Al2O3-MgO-ZrO2 ladle air plug |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN1289241C (en) |
Cited By (16)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1300058C (en) * | 2004-08-25 | 2007-02-14 | 武汉科技大学 | Sailon corundum refractory material for permeable ladle stopper and its prepn process |
| CN102335730A (en) * | 2010-07-26 | 2012-02-01 | 宝山钢铁股份有限公司 | Silicone-free submersed nozzle and manufacturing method thereof |
| CN103086730A (en) * | 2013-03-05 | 2013-05-08 | 江苏诺明高温材料股份有限公司 | Preparation method of magnesium spinelle zirconium eutectic sand |
| CN104084574A (en) * | 2014-07-14 | 2014-10-08 | 浙江铭德新材科技有限公司 | Novel environmentally friendly tundish working lining and forming method thereof |
| CN104245185A (en) * | 2012-02-07 | 2014-12-24 | 维苏威坩埚公司 | Gas purging plug comprising wear indicators |
| CN107032769A (en) * | 2017-06-05 | 2017-08-11 | 武汉科技大学 | A kind of High-Alumina material for repairing and preparation method thereof |
| CN108530090A (en) * | 2018-05-07 | 2018-09-14 | 濮阳濮耐高温材料（集团）股份有限公司柳屯分厂 | A kind of lightweight liner in dundish and preparation method thereof |
| CN108779037A (en) * | 2016-02-05 | 2018-11-09 | 圣戈本陶瓷及塑料股份有限公司 | Chromium oxide refractory body and the method for forming the refractory body |
| CN109111216A (en) * | 2018-09-19 | 2019-01-01 | 华北理工大学 | A kind of magnalium zirconia refractory and its preparation method and application |
| CN109369160A (en) * | 2018-12-04 | 2019-02-22 | 钢城集团凉山瑞海实业有限公司 | Tundish cover castable |
| CN109704733A (en) * | 2019-01-31 | 2019-05-03 | 武汉科技大学 | A kind of gradual change three-dimensional through hole porous plug and preparation method thereof |
| CN111348905A (en) * | 2019-07-08 | 2020-06-30 | 营口石兴耐火材料科技有限公司 | Magnesium oxide micro powder reinforced aluminum zirconium carbon sliding plate and preparation method thereof |
| CN111689765A (en) * | 2020-05-29 | 2020-09-22 | 芜湖市容川机电科技股份有限公司 | Preparation method of casting ladle for casting |
| CN112341167A (en) * | 2020-11-06 | 2021-02-09 | 浙江自立高温科技股份有限公司 | Aluminum-magnesium precast block for refined steel ladle and preparation method thereof |
| CN113477931A (en) * | 2021-07-16 | 2021-10-08 | 山东鲁铭高温材料股份有限公司 | Casting water nozzle for ferrochrome granulation system |
| CN115572156A (en) * | 2022-09-29 | 2023-01-06 | 浙江自立高温科技股份有限公司 | Aluminum-silicon-chromium breathable element without molten steel infiltration and preparation method thereof |
-
2003
- 2003-01-07 CN CN 03118422 patent/CN1289241C/en not_active Expired - Fee Related
Cited By (22)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1300058C (en) * | 2004-08-25 | 2007-02-14 | 武汉科技大学 | Sailon corundum refractory material for permeable ladle stopper and its prepn process |
| CN102335730A (en) * | 2010-07-26 | 2012-02-01 | 宝山钢铁股份有限公司 | Silicone-free submersed nozzle and manufacturing method thereof |
| CN102335730B (en) * | 2010-07-26 | 2013-07-17 | 宝山钢铁股份有限公司 | Silicone-free submersed nozzle and manufacturing method thereof |
| CN104245185A (en) * | 2012-02-07 | 2014-12-24 | 维苏威坩埚公司 | Gas purging plug comprising wear indicators |
| CN104245185B (en) * | 2012-02-07 | 2016-05-18 | 维苏威坩埚公司 | There is the porous plug of wear indicator |
| CN103086730A (en) * | 2013-03-05 | 2013-05-08 | 江苏诺明高温材料股份有限公司 | Preparation method of magnesium spinelle zirconium eutectic sand |
| CN104084574A (en) * | 2014-07-14 | 2014-10-08 | 浙江铭德新材科技有限公司 | Novel environmentally friendly tundish working lining and forming method thereof |
| CN104084574B (en) * | 2014-07-14 | 2016-08-24 | 浙江铭德新材科技有限公司 | A kind of environment-friendly type liner in dundish and forming method thereof |
| CN108779037A (en) * | 2016-02-05 | 2018-11-09 | 圣戈本陶瓷及塑料股份有限公司 | Chromium oxide refractory body and the method for forming the refractory body |
| CN108779037B (en) * | 2016-02-05 | 2021-12-14 | 圣戈本陶瓷及塑料股份有限公司 | Chromium oxide refractory object and method of forming the same |
| CN107032769A (en) * | 2017-06-05 | 2017-08-11 | 武汉科技大学 | A kind of High-Alumina material for repairing and preparation method thereof |
| CN108530090A (en) * | 2018-05-07 | 2018-09-14 | 濮阳濮耐高温材料（集团）股份有限公司柳屯分厂 | A kind of lightweight liner in dundish and preparation method thereof |
| CN109111216A (en) * | 2018-09-19 | 2019-01-01 | 华北理工大学 | A kind of magnalium zirconia refractory and its preparation method and application |
| CN109369160A (en) * | 2018-12-04 | 2019-02-22 | 钢城集团凉山瑞海实业有限公司 | Tundish cover castable |
| CN109704733B (en) * | 2019-01-31 | 2021-06-15 | 武汉科技大学 | Gradual change three-dimensional through hole ventilation plug and preparation method thereof |
| CN109704733A (en) * | 2019-01-31 | 2019-05-03 | 武汉科技大学 | A kind of gradual change three-dimensional through hole porous plug and preparation method thereof |
| CN111348905A (en) * | 2019-07-08 | 2020-06-30 | 营口石兴耐火材料科技有限公司 | Magnesium oxide micro powder reinforced aluminum zirconium carbon sliding plate and preparation method thereof |
| CN111689765A (en) * | 2020-05-29 | 2020-09-22 | 芜湖市容川机电科技股份有限公司 | Preparation method of casting ladle for casting |
| CN112341167A (en) * | 2020-11-06 | 2021-02-09 | 浙江自立高温科技股份有限公司 | Aluminum-magnesium precast block for refined steel ladle and preparation method thereof |
| CN113477931A (en) * | 2021-07-16 | 2021-10-08 | 山东鲁铭高温材料股份有限公司 | Casting water nozzle for ferrochrome granulation system |
| CN113477931B (en) * | 2021-07-16 | 2024-01-19 | 山东鲁铭新型材料股份有限公司 | Pouring water nozzle for ferrochrome granulating system |
| CN115572156A (en) * | 2022-09-29 | 2023-01-06 | 浙江自立高温科技股份有限公司 | Aluminum-silicon-chromium breathable element without molten steel infiltration and preparation method thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| CN1289241C (en) | 2006-12-13 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN1289241C (en) | Preparation method of Al2O3-MgO-ZrO2 ladle air plug | |
| CN100478305C (en) | Aluminum oxide electric furnace cover pouring material and preparation method thereof | |
| CN100410204C (en) | Tundish permeable brick and its preparing process | |
| CN101234905B (en) | Corundum spinel refractory materials for RH lining and manufacturing method thereof | |
| CN101045635A (en) | Ceramic Al203SiC refractory and preparation method thereof | |
| JP2549450B2 (en) | Novel refractory compositions containing monoclinic zirconia and articles formed from the compositions exhibiting improved high temperature mechanical strength and improved thermal shock resistance | |
| CN104774020B (en) | Recycled magnesia carbon coating material with strong slag-corrosion resistance and application thereof | |
| CN110723963B (en) | Blast furnace tapping channel castable containing nano alumina and preparation method thereof | |
| CN114195529B (en) | High-strength magnesia refractory mortar for refining ladle | |
| CN110668830A (en) | Preparation method of novel mullite-combined light castable | |
| CN108033795A (en) | High alumina castable for fish torpedo ladle permanent layer | |
| CN114873995B (en) | Low-expansion high-fracture-resistance tundish retaining wall castable | |
| CA2321843C (en) | Free-flowing basic castable and castings produced therefrom | |
| JPH07330447A (en) | Flow-in refractory material | |
| MXPA05005845A (en) | Heavy ceramic moulded body, method for producing said body and use of the same. | |
| JP2010235342A (en) | Monolithic refractory for blast furnace iron spout | |
| JP2001302364A (en) | Alumina-magnesia-based castable refractory containing zirconium oxide and molten metal vessel for metal refining | |
| CN114478031A (en) | Production process of unburned aluminum-magnesia-carbon brick for electric furnace steel ladle | |
| CN108383534A (en) | A kind of pouring materialfor steel ladle and application method of graphene-containing | |
| CN110436948B (en) | Ceramic blast furnace swinging launder and preparation method thereof | |
| JPH0323275A (en) | Monolithic refractory for casting | |
| JPH06345550A (en) | Castable refractory | |
| CN112552058B (en) | Sintering casting magnesium-aluminum-zirconium-chromium sliding plate and preparation method thereof | |
| JP2001270781A (en) | Castable alumina-magnesia-based refractory using magnesium carbonate as magnesia source | |
| CN116924781B (en) | High-temperature tin bath bottom brick for float glass production and preparation method thereof |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| EE01 | Entry into force of recordation of patent licensing contract |
Assignee: Wuxi Nanfang Refractory Co., Ltd. Assignor: Wuhan University of Science and Technology Contract fulfillment period: 2006.12.26 to 2012.12.26 contract change Contract record no.: 2008320000494 Denomination of invention: Preparation method of Al#-[2]O#-[3]-MgO-ZrO#-[2] quality ladle air vent plug Granted publication date: 20061213 License type: Exclusive license Record date: 2008.10.6 |
|
| C19 | Lapse of patent right due to non-payment of the annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee | ||
| LIC | Patent licence contract for exploitation submitted for record |
Free format text: EXCLUSIVE LICENSE; TIME LIMIT OF IMPLEMENTING CONTACT: 2006.12.26 TO 2012.12.26; CHANGE OF CONTRACT Name of requester: WUXI CITY SOUTHERN CO. RESISTANCE MATERIAL CO., LT Effective date: 20081006 |