WO2016137210A1 - Alliage de magnésium à déformation plastique ayant d'excellentes conductivité thermique et ininflammabilité et procédé de préparation associé - Google Patents

Alliage de magnésium à déformation plastique ayant d'excellentes conductivité thermique et ininflammabilité et procédé de préparation associé Download PDF

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WO2016137210A1
WO2016137210A1 PCT/KR2016/001770 KR2016001770W WO2016137210A1 WO 2016137210 A1 WO2016137210 A1 WO 2016137210A1 KR 2016001770 W KR2016001770 W KR 2016001770W WO 2016137210 A1 WO2016137210 A1 WO 2016137210A1
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magnesium
alloy
thermal conductivity
flame retardancy
magnesium alloy
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Korean (ko)
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이인영
김강형
전현석
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C23/00—Alloys based on magnesium
    • C22C23/04—Alloys based on magnesium with zinc or cadmium as the next major constituent
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C1/00—Making non-ferrous alloys
    • C22C1/02—Making non-ferrous alloys by melting
    • C22C1/03—Making non-ferrous alloys by melting using master alloys
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/002—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working by rapid cooling or quenching; cooling agents used therefor
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/06—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of magnesium or alloys based thereon

Definitions

  • the present invention imparts plastic workability by adding 0.5-5% by weight of zinc to the magnesium (hereinafter,% by weight) to solid solution, and contains 0.6-3.5% by weight of tin (Sn) as a high melting point oxide film forming element, if necessary.
  • Thermal conductivity and flame retardancy of 2.5 to 6.3% by weight of the total alloying elements are added by selectively adding at least 1.5% by weight or less of calcium (Ca), silicon (Si), manganese (Mn) and mischmetal (Mischmetal).
  • the present invention relates to a magnesium alloy having excellent plasticity and easy to process.
  • magnesium alloy is currently the lightest metal among the commercially available metal materials, and the use of magnesium alloy is rapidly expanding as a material of various parts in place of aluminum in the metal material usage to achieve further weight reduction.
  • the demand for fuel economy and the application to mobile electronics are increasing rapidly.
  • Magnesium alloys have the lightest density of 1.74 g / cc among commercially available structural alloys, which is two-thirds the density of aluminum.
  • magnesium alloy has excellent machinability, high vibration damping property, excellent absorbency against vibration and shock, excellent electromagnetic shielding function, and the like.
  • the reason for the rapid expansion of magnesium alloy into computers, mobile phones, automobile parts, etc. in recent years is that it has excellent light weight and reproducibility, shielding against electromagnetic waves, and is capable of forming as a thin shape such as castability superior to aluminum. Because.
  • magnesium has a dense hexagonal lattice structure with a small slip system, which is essential for plastic deformation, and is mainly formed by casting due to poor extrudability and formability.
  • sand casting has many limitations in shape, and molding by die casting causes many problems in subsequent surface treatment processes because the cast structure is porous in its characteristics.
  • materials such as AZ31 and AM20 alloyed with aluminum and zinc or manganese were developed to enable plastic processing using the ductility of single-phase solid solution.
  • they have developed an anisotropy in one direction due to the development of the bottom surface tissue after annealing and strong anisotropy and easy formation of tensile twins. .
  • AZ-based and AM-based magnesium alloys are formed of an initial precipitate of high-melting point iron-based impurities (Fe, Ni) or copper (Cu) having low solid solubility during solidification, and then beta Mg 17 Al 12 Since the compounds make coarse plate-like precipitates, and these precipitates are linked to interfere with heat transfer, there is a problem that the thermal conductivity is greatly lowered even if the amount is about 3-4%. (Ed. GL Song, Corrosion of Magnesium Alloys, 2011, pp. 137-146)
  • alloys such as WE43, ZE41, ZE10 or Elektron 21, which are yttrium, niobium (Nb), samarium (Sm), ytterbium (Yb), gadolium (Gd), neodymium (Nd) and zirconium It is an alloy containing a rare earth element such as (Zr). These alloys are excellent in flame retardancy due to the strong oxide film of rare earth elements, but they do not satisfy the demands of the market because they require large amounts of expensive elements or poor plasticity.
  • the thermal conductivity decreases as the amount of the alloying element is increased.
  • zirconium is an element that refines the grain size and improves flame retardancy, but has a very low thermal conductivity and plastic workability. As a result, about 1% of magnesium is added to reduce the thermal conductivity by 50 to 70%.
  • WE43 with zirconium added has 51 ⁇ 54W / m-K and ZE41 has 24W / m-K thermal conductivity and low ductility, so it is mainly used as casting material rather than plastic processing.
  • Elektron 21 contains about 4% of rare earth elements and 0.5% or less of zinc, which is excellent in thermal conductivity of 116W / m-K and excellent in suppressing ignition but very low in elongation of 2%.
  • ZE10 is also difficult to use for plastic processing in the industry because it is formed by special method such as ECAP because of low thermal conductivity and plastic processability by addition of zirconium.
  • Korean Patent Registration No. 10-1367892 introduces a high temperature magnesium alloy magnesium alloy and a manufacturing method, which combines aluminum and calcium as the calcium oxide is reduced by adding 0.5 to 3.8% by weight of calcium oxide (CaO) to the magnesium alloy molten metal. To impart flame retardancy.
  • this alloy also has a disadvantage that the plastic workability is significantly reduced.
  • Korean Patent No. 10-0509648 introduces a method of manufacturing a magnesium alloy sheet having excellent plastic workability by adding zinc and yttrium to magnesium.
  • the molten metal containing 0.5-5.0% of zinc and 0.2-2.0% of yttrium was cast in a plate shape of 35 mm thickness and rolled to 1.0 mm plate through annealing to improve the plastic workability of the rolled plate material.
  • no solution has been provided for the segregation of the core and the specific gravity segregation of zinc, which is increased when 3% or more of zinc is added.
  • the method of improving the flame retardancy of the material was not considered at all.
  • the thermal conductivity of this alloy is improved by 75% compared to that of AZ91 and is only 87 W / mK, similar to AZ31, which is less than the thermal conductivity of 100 W / mK expected in the present invention.
  • Korean Patent No. 10-1276665 a magnesium alloy capable of plastic processing solved flame retardancy with an alloy based on magnesium (Sn) 4-10% and calcium (Ca) 0.05-1.0%.
  • Sn magnesium
  • Ca calcium
  • due to the problem of maintaining the melt temperature at 850 ⁇ 900 °C to dissolve high melting point elements such as calcium, manganese, yttrium, erbium unnecessarily increases the gas concentration and the oxide in the melt to increase the impurity concentration
  • Korean Patent Registration No. 10-1406111 introduces an alloy in which 6.5-7.5% of tin, 1% of zinc and aluminum are added to magnesium.
  • Korean Patent No. 10-0519721 discloses a high-strength magnesium alloy in which magnesium is 6% zinc as a basic composition and 0.4-3% of manganese, aluminum, silicon, and calcium are additionally added.
  • magnesium is 6% zinc as a basic composition
  • manganese, aluminum, silicon, and calcium are additionally added.
  • a large amount of zinc may cause specific gravity segregation, which may cause the billet to break during extrusion or deteriorate in plastic workability.
  • the high strength and plastic workability are mentioned. There was no basis for predicting gender performance.
  • magnesium alloys were initially developed to be inclined to plastic processability or to be flame retardant.
  • thermal conductivity and flame retardancy and securing plastic processability This is because structural materials are not simply satisfied with strength and formability in order to commercialize, and safety can be ensured by preventing the spread of fire only by suppressing the ignition property of magnesium material when a fire occurs.
  • fire must not ignite within two minutes of exposure to an oil burner flame for four minutes (240 seconds), and within three minutes after the burner is turned off. A total of 7 minutes of flame retardancy tests to be extinguished shall meet the specification if no more than 10% of the initial weight is lost.
  • Figure 1 shows a schematic of the aircraft magnesium alloy flame retardancy test apparatus and specimen approved by FAA.
  • the present invention was created to eliminate the above problems, and contains 0.5 to 5% by weight of zinc (Zn) and 0.6 to 3.5% by weight of tin (Sn) as a high melting point oxide forming element, but calcium (Ca) if necessary ), Silicon (Si), manganese (Mn) and mischmetal (Mischmetal) by selectively adding 1.5% by weight or less to manage the total amount of alloying elements from 2.5 to 6.3% by weight, excellent thermal conductivity and flame retardancy While the plastic workability is improved, extrusion is possible even at a pressure of 1000 kgf / cm 2 or less, and an object of the present invention is to provide a magnesium alloy for annealing and a method for producing the alloy having excellent thermal conductivity and flame retardancy of 100 W / mK or more.
  • the present invention contains 0.5 to 5% by weight of zinc and 0.6 to 3.5% by weight of tin (Sn) as a high-melting-point oxide film-forming element, but if necessary, calcium (Ca), silicon (Si), and manganese.
  • Sn tin
  • Mn and Mischmetal selectively add one or more of Mn and Mischmetal to 1.5 wt% or less to manage the total amount of alloying elements at 2.5 to 6.3 wt% to obtain a magnesium alloy having excellent thermal conductivity and flame retardancy and improved plastic workability.
  • high melting point elements other than zinc and stocks are added in the form of a mother alloy, and mechanical stirring is performed to remove component segregation and to cast. Thereafter, after removing the surface coating structure of the casting material and performing diffusion annealing, it is then molded into a predetermined shape through an annealing process such as rolling, extrusion or forging.
  • the high malleability of the magnesium alloy can be plasticized without surface defects even at an extrusion pressure of 1000 kgf / cm 2 or less, and has excellent flame retardancy and thermal conductivity, and thus requires heat conduction required in portable home appliances, automobiles, aircraft parts, and the like.
  • satisfactory performance and flame retardancy there is an effect of providing a magnesium alloy extruded material which can be usefully used at a low cost.
  • FIG. 1 is a schematic view of a flame retardant test apparatus and specimen.
  • Figure 2 is a schematic diagram showing the stirring process during mold cooling.
  • FIG. 10 is a high temperature stable phase precipitated state diagram of alloy 8.
  • FIG. 13 is a high temperature stable phase precipitation state diagram of Alloy 11.
  • FIG. 14 is a high temperature stable phase precipitation state diagram of Alloy 12.
  • 17 is a high temperature stable phase precipitation state diagram of an alloy 15 comparative example.
  • Fig. 19 shows a casting structure of alloy 10.
  • Fig. 21 is an extruded material structure of alloy 6.
  • 22 is an extruded material structure of alloy 7.
  • 26 is a flame retardant test scene.
  • the present invention contains 0.5 to 5% by weight of zinc in magnesium and 0.6 to 3.5% by weight of tin (Sn) as a high melting point oxide forming element, but if necessary, calcium (Ca), silicon (Si), manganese (Mn) and misc
  • tin tin
  • Ca silicon
  • Mn manganese
  • misc By selectively adding at least 1.5% by weight or less of the metal (Mischmetal) to manage the total amount of alloying elements at 2.5 to 6.3% by weight, not only has thermal conductivity and flame retardancy, but also high melting point alloying elements are added as a master alloy to provide 720 It can melt
  • Zinc is dissolved in Mg to change the c / a axis ratio, thereby inhibiting the development of the bottom aggregate tissue, and uniform solid working is possible due to the work hardening effect of MgZn 2 and MgZn 5 precipitates in solid solution.
  • less than 0.5% is less effective, so it is difficult to expect the work hardening and malleability required for plastic processing materials, and when it exceeds 5%, the bottom aggregate structure, which inhibits formability after annealing, is strengthened.
  • the precipitated phases such as Mg 2 Zn 3 and Mg 12 Zn 13 are laminated with the alpha phase to form a low melting point process phase around 340 ° C., thus limiting flame retardancy.
  • Tin improves high-temperature plasticity by making Mg 2 Sn precipitates, which are stable at high temperatures above 560 °C and by appropriately distributing them, and when exposed to flames in the air, contributes to the improvement of flame retardancy by forming SnO 2 oxide films with melting points above 1600 °C.
  • the addition amount when the addition amount is less than 0.6%, it is difficult to expect the effect. If the addition amount is more than 3.5%, the melting point is lowered and the ignition point may be lowered below 500 ° C., thereby impairing the flame retardancy, and the excessive amount of Mg 2 Sn precipitates. Since not only the malleability falls but also the manufacturing cost rises, 1.0 to 3.0% is preferable.
  • Mischmetal is a rare earth alloy containing 65% to 78% of cerium (Ce) and lanthanum (La), and the rest is neodymium (Nd), praseodymium (Pr) and indispensable impurities. Mischmetal is used as a substitute for lanthanum for cost savings because it is cheaper and has the same effect as lanthanum (La) or cerium (Ce), which have a lanthanum effect in magnesium alloy. Cerium and neodymium also exhibit flame retardancy by forming oxide films such as CeO 2 and Nd 2 O 3 with melting points of 2400 ° C and 2200 ° C, respectively, when exposed to flames in the atmosphere. Due to the high temperature stable phase, the high temperature strength is kept high, and the property of suppressing warpage, sagging or premature melt bar-separation at high temperatures by the flame is strong.
  • the present invention is limited to 1.5% or less.
  • the reason why the constituent elements in the rare earth metal are expressed by the mismetal is that the cost increases when the constituent elements are added as a single metal. Therefore, the addition of the constituent elements alone does not depart from the scope of the present invention.
  • Lanthanum is used as a substitute for misch metal in the present invention.
  • the high solubility limit of magnesium is 12.4%, and it is combined with MgZn 2 precipitate to form a long period stacking order structure of hexagonal system.
  • Precipitates are formed to form a lamellar lamellar process phase at the grain boundaries.
  • Precipitates are transformed into homogeneous intermetallic compounds through spinodal decomposition during homogenization heat treatment after casting, and dispersed during annealing to contribute to strengthening dispersion.
  • a La 2 O 3 oxide film having a melting point of 2300 ° C. or more is formed to exhibit flame retardancy.
  • the high temperature stable phase due to the high temperature stable phase, the high temperature strength is maintained, and the property of suppressing warpage, sag or premature melt bar-separation at high temperatures due to the flame is strong.
  • the precipitate tends to be coarse with increasing amount, so it is limited to 1.5% or less.
  • Mg 2 Ca is a group 2 alkaline earth metal such as magnesium.
  • Mg 2 Ca which has a melting point of 715 ° C, which is a secondary coagulation phase, is formed between dendritic tissues or is employed in a matrix with zinc, causing recrystallization in a disordered direction during heating. It has the effect of inhibiting development and miniaturizing grains, and improves flame retardancy by forming a CaO oxide film having a melting point of 2600 ° C. or more when exposed to flame in the air.
  • the high temperature stable phase the high temperature strength is maintained, and the property of suppressing warpage, sag or premature melt bar-separation at high temperatures due to the flame is strong.
  • the amount of Mg 2 Ca particles is excessively increased and the malleability may decrease, so the amount is limited to 1.5% or less.
  • a high temperature stable phase such as Mg 2 Si is formed to refine the grain size and exert a precipitation strengthening effect.
  • the precipitate is easy to coarse, but the addition of calcium can adjust the size or shape of the precipitate.
  • a SiO 2 oxide film having a melting point of 1600 ° C. or more is formed to exhibit flame retardancy. Due to the high temperature stable phase, the high temperature strength is kept high, and the property of suppressing warpage, sagging or premature melt bar-separation at high temperatures by the flame is strong.
  • the present invention is limited to 1.5% or less because the precipitate begins to coarsen with increasing amount.
  • Manganese has a maximum solubility of 2.2% in magnesium.
  • Magnesium alloys have a crystallization reaction in which the alpha phase of manganese precipitates and the excitation reaction in which the delta phase precipitates at 650 ° C., thereby minimizing grain size and improving corrosion resistance.
  • when exposed to a flame in the atmosphere has an effect of improving the flame retardancy by forming a MnO oxide film having a melting point of more than 1900 °C.
  • it is effective to refine the coarse plate-shaped Mg 17 Al 12 precipitate formed when aluminum is present as an impurity and to refine the MgZn 2 precipitate during recrystallization during annealing.
  • the present invention is limited to 1.5% or less because the effect is saturated and the malleability decreases as the amount added increases.
  • molten metal is prepared by selectively adding one or more kinds of metals (Mischmetal) to 1.5 wt% or less and undergoing mechanical stirring during the solidification process, the malleability is ensured to be extruded at a pressure of 1000 kgf / cm2 or less and exposed to flame.
  • a high melting point oxide film is formed on the surface of the material to exhibit flame retardancy, satisfies thermal conductivity at the same time, thereby preventing the occurrence of premature melting due to local heating and shortening the self-extinguishing time of the melted material.
  • the reason for managing the total amount of alloying elements in the present invention at 2.5 to 6.3% is less effective at improving the malleability and flame retardancy at less than 2.5%, and when the alloying elements are added in excess of 6%, compounds and precipitates are excessively high in thermal conductivity. It lowers, and since it has low malleability and melting point, it limits.
  • the ignition is suppressed and the flame retardancy is improved.
  • the melting point of the material is lowered and the thermal diffusion rate is also lowered as the amount is increased.
  • the total amount of the alloy is suppressed to 6.3% or less.
  • the thermal conductivity is lowered.
  • Aluminum contains a large amount of coarse plate-shaped Mg 17 Al 12 which contains only about 3%, which lowers thermal conductivity and consumes rare earth or alkaline earth elements and impairs flame retardancy. Therefore, aluminum is limited to 1% or less as impurities. .
  • zirconium combines with other rare earth elements in the dendritic structure at the grain boundary to form lamellae, the zirconium is limited to 0.5% or less because it significantly lowers the thermal conductivity and increases the brittleness, thereby deteriorating the malleability.
  • the thermal conductivity of 100 W / mK or more is exhibited by the above-described method, and tin (Sn), calcium (Ca), silicon (Si), manganese (Mn) and mischmetal (Mischmetal) as high melting point oxide film forming elements. It is characterized by satisfying the flame retardancy of more than 120 seconds of ignition time, less than 180 seconds of specimen extinguishing time after burner extinguishing, weight loss of 10% or less in the burner ignition test.
  • high melting point alloy elements excluding calcium and tin, which are low melting points in alloys (calcium, silicon, manganese, misc metal, lanthanum) They are added to the master alloy and characterized in that the molten metal is mechanically stirred.
  • Magnesium alloys often have a large difference in specific gravity between magnesium and other alloying elements.
  • zinc and tin tend to segregate in the center or under the mold, and coarse development of dendritic crystals leads to uneven macroscopic composition of billets. It causes a decrease in extrusion performance.
  • hot tearing occurs in the center of billet, which causes deformation, cracking, and fine wrinkles during the extrusion process. And reliability.
  • a high melting point alloying element as a mother alloy, it is possible to dissolve while managing the temperature of the melt at 720 ° C. or lower, thereby lowering the possibility of ignition of the melt, and the coagulation nucleus already formed in the mash zone in the melt through mechanical stirring.
  • By dispersing it it is possible to promote uniform solidification in the molten metal, to reduce segregation and to refine grains.
  • magnesium alloy does not have unpaired hole electrons, so the magnetization power is weak, so that it is difficult to obtain a sufficient magnetic stirring effect, and mechanical stirring is effective.
  • the method of manufacturing the master alloy lowers the melting point of the master alloy by forming a lump or granule, the main component of which is to be alloyed in the molten magnesium, in a shielding gas atmosphere shielding from the atmosphere, and by mechanically stirring the composition near the process composition. .
  • the total component segregation difference between the upper and lower parts of the casting material was less than 1% when mechanical stirring was performed during gravity casting of 30 kg magnesium alloy billet containing 4% zinc. There was more than 8% segregation difference. Therefore, it can be seen that mechanical stirring is effective for removing segregation. This segregation causes the billet to break at the segregation boundary during extrusion, or remains after extrusion, causing visual defects and uneven physical properties.
  • a stirring method using a motor and an impeller will be described as a method of mechanical stirring.
  • the use of attraction or other mechanical agitation does not detract from the effects sought in the scope of the present invention.
  • the casting material for example, billet
  • the casting material subjected to mechanical agitation when the molten metal is stirred while the solidification process proceeds inside disperses the high temperature stable phase and the high temperature precipitates formed as solids in the melt zone in the molten metal, thereby acting as a solidification core.
  • the structure of the casting material is uniform, segregation is eliminated, and the grains are effective.
  • the molten alloy is blocked from the atmosphere by the shielding gas injected through the cover 3 and the shielding gas pipe 4 combined with the crucible or the mold 1. While the billet is solidifying, the alloy composition is made uniform by inserting and stirring a small impeller 22 into a molten stainless steel lever 21 which is operated by a motor M through a through hole provided in the cover. By moving up and down to the marsh zone 8, the coagulation nuclei can be dispersed to refine the crystals. Impeller 22 used in the present invention is also included in the scope of the present invention using other metals, ceramic materials, composite materials, or depositing, plating, penetrating or spray coating other materials on the impeller.
  • the diameter of the impeller is 1/5 to 2/3 of the diameter of the billet. If the diameter of the impeller is larger than this, it is limited because it requires a large motor due to the load. In addition, if less than 1/5 of the billet diameter, the stirring effect is insignificant, which is not suitable for segregation prevention.
  • the magnesium alloy when producing the magnesium alloy molten magnesium is first dissolved in the crucible and the temperature is maintained at 680 ⁇ 720 °C.
  • the crucible was made of stainless steel, and the melting atmosphere shields contact with the atmosphere by flowing a gas mixed with 0.25 to 0.3% SF 6 in carbon dioxide gas. Then, zinc and / or tin are added as alloying elements, and other high melting point alloying elements (mischmetal, lanthanum, calcium, silicon, manganese) are added in the form of a master alloy close to the process composition.
  • the crucible is extracted and charged into a cooling bath. In this process, the refrigerant is injected or charged into a tank filled with a refrigerant, such as water of 30 ° C. or lower, to cool the crucible to promote solidification of the molten metal.
  • the crucible When cooling in a bath, the crucible is cooled at a rate of about 70-200 ° C / min depending on the capacity of the bath and the temperature of the refrigerant. If cooling by injecting the refrigerant, the cooling rate is higher, and when the crucible is sprayed and cooled in a water tank, it is cooled at a cooling rate of about 200 ⁇ 600 °C / min. In continuous casting where the solidification speed is to be increased, the mold and billet are increased by increasing the injection pressure. Intense cooling can result in cooling at a rate of about 400-900 ° C / min. However, if the cooling rate exceeds 900 °C / min, there is a problem that the crack in the center due to the heat shrinkage stress due to the cooling rate difference inside and outside the billet.
  • an impeller made of stainless steel is inserted into a crucible to mechanically stir the molten metal two or three times to disperse the coagulation nuclei formed in the cast material, thereby obtaining a cast material having a low segregation and a fine structure.
  • the surface chill (Chill) structure was removed to obtain a billet having a diameter of 74 ⁇ 75mm, and was subjected to diffusion annealing at 380 °C for 2 hours and cooled to room temperature.
  • the diffusion-unfolded billet was preheated at 380 ° C. for 1.5 hours, and the alloys of Table 1 were extruded from an extrusion die to form a sheet having a width of 50 mm and a thickness of 8 mm.
  • Example alloys of Table 1 were mostly extruded at 750-900 kgf / cm 2 pressure. However, the alloys of Comparative Examples 1 and 15 were extruded, but due to the low melting point process, microcracks exist on the surface of the plate. In Comparative Example 14, the extrusion temperature was lowered to around 340 ° C. and the extrusion pressure was increased to 1500 kgf / cm 2. Surface microcracks could be prevented, but after the burner was removed in the flame retardancy test, the natural digestion time was exceeded, and the weight loss was excessive.
  • the plate-like sample thus obtained was diffused and unannealed at 380 ° C. for 1 hour and processed into a diameter of 12.7 mm and a thickness of 2 mm, and thermal conductivity was measured by a laser flash method according to ASTM E4161.
  • the alloys of the present invention were 125 W / mK at a high temperature of 100 ° C. or higher. It was confirmed to exhibit the above thermal conductivity.
  • the ignition point of the processed chip obtained from the sample was measured by thermogravimetric analysis (TGA) using a differential scanning calorimeter (DSC), and a flame retardancy test was performed using a burner by processing a specimen having a width of 38.1 mm, a thickness of 6.4 mm, and a length of 508 mm. Each was carried out twice.
  • TGA thermogravimetric analysis
  • DSC differential scanning calorimeter
  • the alloys of the present invention have a ignition point of more than 550 ° C., a ignition time of 120 seconds or more, a burner digestion within 180 seconds of spontaneous fire extinguishing, satisfactory flame retardant conditions of less than 10% weight loss, plastic workability, and thermal conductivity. Doing.
  • the example alloys of the present invention were produced in 4.4 ⁇ 6.0% range showed excellent thermal conductivity and flame retardancy, yet easy plastic processing.
  • 3 to 17 is a high temperature stable phase precipitation state diagram of the alloys and comparative alloys according to the present invention
  • the high temperature stable phase begins to appear at least 430 °C or more in the state diagram of the comparative example is insufficient or excessively excessive precipitation of the high temperature stable phase
  • 18 to 23 show the structure of the alloy of the present invention. Looking at the precipitates of the cast structure in Figure 18 to 20 was suppressed the formation of coarse lamellae in the grain boundary, it can be seen that the precipitates are finely dispersed during the extrusion process in Figure 21 ⁇ Figure 23 of the extruded material.
  • 24 to 25 is a thermal conductivity measurement graph of the present invention, as shown in Table 1, the alloy of the present invention has a thermal conductivity of 115W / mK or more 51 ⁇ 54W / of WE43 used as a conventional AZ-based alloy or currently flame retardant alloy Compared with the 24W / mK of mK and ZE41, it shows higher thermal conductivity and satisfies the flame retardancy test.
  • Figure 26 is a flame retardant test scene of the present invention, the alloy of the present invention has the effect of improving the flame retardancy due to the small effect of shortening the melt time by the local heating when it touches the flame due to the excellent thermal conductivity.
  • cover 4 shielding gas piping
  • injection hole 6 continuous casting billet support
  • Coolant injection nozzle 8 Mashed zone

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Abstract

La présente invention concerne un alliage de magnésium ayant d'excellentes conductivité thermique et ininflammabilité et facilitant la déformation plastique, ainsi qu'un procédé de préparation associé. L'alliage de magnésium contient de 0,5 à 5 % en poids de zinc (Zn) et, à titre d'élément de formation de film d'oxyde à point de fusion élevé, de 0,6 à 3,5 % en poids d'étain (Sn) dans le magnésium. La quantité totale d'éléments d'alliage est comprise entre 2,5 et 6,3 % en poids en ajoutant sélectivement 1,5 % en poids ou moins de calcium (Ca) et/ou de silicium (Si) et/ou de manganèse (Mn) et/ou de mischmetal, si nécessaire. Le procédé de préparation de l'alliage comprend les étapes consistant à : ajouter des éléments d'alliage à point de fusion élevé sous la forme d'un alliage maître à un alliage fondu de magnésium et de zinc; faire fondre ledit alliage maître; le couler; retirer la zone de refroidissement d'un matériau coulé; réaliser un recuit de diffusion; et effectuer un moulage par l'intermédiaire d'un processus de trempe, tel qu'un laminage, une extrusion ou un forgeage. La présente invention a pour effets : d'améliorer la ductilité du fait que l'action des éléments d'alliage inhibe la formation de précipités de type plaque dans une texture à base de magnésium; de permettre une extrusion même à une pression inférieure ou égale à 1000 kgf/cm2 puisque la déformabilité plastique d'un alliage de magnésium est améliorée; de permettre une large application de l'alliage à titre de plaque de rayonnement ou de matériau structural d'appareils électriques domestiques portables, de pièces d'automobile et d'avion, et autre, puisque la présente invention est appropriée pour une utilisation nécessitant une sécurité incendie du fait qu'elle présente une conductivité thermique supérieure ou égale à 100 W/m•K et une ininflammabilité satisfaisant les exigences relatives à l'utilisation d'un matériau pour avion; et de contribuer à la réduction du poids.
PCT/KR2016/001770 2015-02-25 2016-02-24 Alliage de magnésium à déformation plastique ayant d'excellentes conductivité thermique et ininflammabilité et procédé de préparation associé Ceased WO2016137210A1 (fr)

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CN110317984A (zh) * 2019-07-04 2019-10-11 重庆电子工程职业学院 一种具有优异韧性的阻燃镁合金复合材料及其制备方法
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CN120041733A (zh) * 2025-04-25 2025-05-27 太原理工大学 高强耐蚀低合金化Mg-Zn-Nd-Ca-Sn-Zr合金及其制备方法

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