A graphene-based coating for aluminum alloys, method of preparation and use thereof

Abstract

The application relates to the technical field of coatings, and discloses an aluminum alloy surface coating based on graphene, a preparation method and application thereof. The aluminum alloy coating prepared by the application is formed by mixing and heating curing of bisphenol A type epoxy resin and epoxy modified water-based acrylic resin as film forming substances, nano silicon dioxide, modified graphene, a coupling agent, diethylenetriamine, phthalic anhydride and other additives, so as to provide basic adhesion and mechanical properties; wherein the addition of the modified graphene significantly improves the corrosion resistance of the coating.

Description

Technical Field

[0001] This invention relates to the field of coating technology, specifically to a graphene-based aluminum alloy surface coating, its preparation method, and its application. Background Technology

[0002] Aluminum alloys are widely used in aerospace, automotive manufacturing, marine engineering, and consumer electronics due to their high specific strength, excellent thermal and electrical conductivity, and good machinability. However, aluminum alloys are chemically reactive, especially in corrosive environments such as those containing chloride ions, where they are prone to pitting corrosion and intergranular corrosion, which seriously affect their service life and structural safety.

[0003] Traditional aluminum alloy corrosion protection methods mainly rely on chromate conversion coatings and anodizing. Although these technologies are mature and effective, hexavalent chromium, due to its high toxicity and carcinogenicity, has been strictly restricted and prohibited by international environmental regulations (such as REACH and RoHS). Anodizing processes, on the other hand, suffer from high energy consumption and brittle films. Therefore, developing new environmentally friendly, efficient, and high-performance green protective technologies has become an urgent need and an important research direction in the field of surface engineering. Organic coatings (such as epoxy resins and polyurethane coatings) are currently the most commonly used physical barrier corrosion protection methods. They provide protection by isolating the metal substrate from the corrosive environment. However, traditional organic coatings form micropores and defects during the curing process, and are prone to microcracks due to mechanical damage during long-term use, leading to the penetration of water, oxygen, and corrosive ions, ultimately causing corrosion of the metal beneath the coating. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a graphene-based aluminum alloy surface coating, its preparation method, and its application.

[0005] The objective of this invention can be achieved through the following technical solutions: A graphene-based aluminum alloy surface coating comprises the following raw materials in parts by weight: 50-70 parts of type A epoxy resin, 15-25 parts of epoxy-modified waterborne acrylic resin, 5-10 parts of nano-silica, 8-15 parts of modified graphene, 10-15 parts of diethylenetriamine, 4-10 parts of phthalic anhydride, 2-4 parts of coupling agent, and 60-100 parts of reactive diluent. Furthermore, the active diluent is ethylene glycol diglycidyl ether; Furthermore, the coupling agent is one of the silane coupling agents KH550, KH560, or KH570; The modified graphene is prepared by the following steps: Step A1: Mix graphene, sodium dodecyl sulfate and water evenly, and then sonicate at 600-700W for 3 hours to obtain graphene dispersion. Furthermore, in step A1, the ratio of graphene, sodium dodecyl sulfate, and water is 1g:2.5-5.5g:100mL; Step A2: Nickel nitrate hexahydrate, cobalt nitrate hexahydrate, and terephthalic acid are stirred evenly in a mixture of N,N-dimethylformamide, ethanol, and water. Then, graphene dispersion is added and stirred for 30 minutes. The mixture is then transferred to a polytetrafluoroethylene reactor and hydrothermally reacted at 130-150℃ for 24-48 hours. After filtration, washing, and vacuum drying, GR@Co / Ni-MOF (Co / Ni-MOF supported graphene) is obtained. Further, in step A2, the ratio of nickel nitrate hexahydrate, cobalt nitrate hexahydrate, terephthalic acid, N,N-dimethylformamide, ethanol, water, and graphene dispersion is 0.005-0.01 mol: 0.01 mol: 0.015-0.02 mol: 50 mL: 5 mL: 5 mL: 5-10 mL; Step A3: Disperse benzotriazole evenly in acetone, add GR@Co / Ni-MOF and stir at room temperature for 2 hours, evacuate for 30 minutes, and then ventilate to the atmosphere for 15 minutes. Repeat the above steps of evacuation and ventilation to the atmosphere three times, wash and dry to obtain modified graphene. Furthermore, in step A3, the ratio of benzotriazole, acetone, and GR@Co / Ni-MOF is 1-3g:100mL:0.1-0.5g.

[0006] A method for preparing a graphene-based aluminum alloy surface coating includes the following steps: Step S1: Weigh the raw materials according to the weight parts, add epoxy resin, epoxy modified waterborne acrylic resin and reactive diluent to the mixer, stir at 50-70 rpm / min for 15-25 min, then add nano silica, modified graphene and coupling agent, stir at 80 rpm / min for 20-30 min, and finally add diethylenetriamine and phthalic anhydride, stir at 100 rpm / min for 5-10 min to obtain the corrosion resistant coating; Step S2: Using 6061 aluminum alloy as the base material, the aluminum alloy sample is polished with 2000# SiC sandpaper and cleaned with 99.99% alcohol. After cleaning, the aluminum alloy is placed in a 60wt% phosphoric acid alcohol solution for electrochemical polishing to obtain the pretreated aluminum alloy. Furthermore, the electrochemical polishing conditions in step S2 are: 20 A / dm² 2 ,20min, aluminum alloy as anode, stainless steel plate as cathode; Step S3: Use a spin coater to uniformly coat the pretreated aluminum alloy surface with a corrosion-resistant coating, and then place it at 80-100℃ to cure it into a film, thus obtaining the graphene-based aluminum alloy surface coating.

[0007] The present invention also includes the application of the above-mentioned graphene-based aluminum alloy surface coating or preparation method to the surface of aluminum alloy products to improve their corrosion resistance.

[0008] The beneficial effects of this invention are: The coating for aluminum alloys prepared by this invention uses bisphenol A type epoxy resin and epoxy-modified waterborne acrylic resin as film-forming substances to provide basic adhesion and mechanical properties. It is formed by adding additives such as nano-silica, modified graphene, coupling agent, diethylenetriamine and phthalic anhydride and then heating and curing. Among them, the addition of modified graphene significantly improves the corrosion resistance of the coating.

[0009] Modified graphene acts as a physical barrier and chemical release agent in coatings. Graphene, as a substrate, possesses an extremely large specific surface area and a very high aspect ratio. When dispersed in epoxy resin, it forms a labyrinthine barrier pathway, significantly extending the path of corrosive media penetration and effectively inhibiting the passage of water, oxygen, and ions. Simultaneously, graphene itself is chemically stable and has good electrical conductivity, effectively blocking the ionic and electronic pathways required for electrochemical corrosion. Furthermore, the in-situ synthesis of MOFs on the graphene surface avoids graphene re-aggregation. MOF particles are anchored on the graphene surface, increasing their compatibility and dispersion stability in epoxy resin. The porous structure of MOFs also provides mechanical interlocking with polymer chains, enhancing interfacial bonding. Its highly ordered and tunable pore structure allows these micropores to effectively adsorb and capture corrosive ions (such as Cl-) penetrating the coating. - This reduces the number of corrosion agents reaching the metal surface. Benzotriazole, a commonly used corrosion inhibitor for aluminum alloys, is released when the corrosive medium (moisture) comes into contact with the MOF. Detailed Implementation

[0010] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0011] Example 1: Modified graphene was prepared by the following steps: Step A1: Mix graphene, sodium dodecyl sulfate and water evenly, and then sonicate at 600W for 3 hours to obtain graphene dispersion. The ratio of graphene, sodium dodecyl sulfate and water is 1g:2.5g:100mL. Step A2: Nickel nitrate hexahydrate, cobalt nitrate hexahydrate, and terephthalic acid are stirred evenly in a mixture of N,N-dimethylformamide, ethanol, and water. Then, graphene dispersion is added and stirred for 30 minutes. The mixture is then transferred to a polytetrafluoroethylene reactor and hydrothermally reacted at 130°C for 24 hours. After filtration, washing, and vacuum drying, GR@Co / Ni-MOF is obtained. The ratio of nickel nitrate hexahydrate, cobalt nitrate hexahydrate, terephthalic acid, N,N-dimethylformamide, ethanol, water, and graphene dispersion is 0.005 mol: 0.01 mol: 0.015 mol: 50 mL: 5 mL: 5 mL. Step A3: Disperse benzotriazole evenly in acetone, add GR@Co / Ni-MOF and stir at room temperature for 2 hours, evacuate under vacuum for 30 minutes, and then ventilate under atmospheric pressure for 15 minutes. Repeat the above vacuuming and atmospheric ventilating steps three times. Wash and dry to obtain modified graphene. The ratio of benzotriazole, acetone and GR@Co / Ni-MOF is 1g:100mL:0.1g.

[0012] A method for preparing a graphene-based aluminum alloy surface coating includes the following steps: 50 parts epoxy resin, 15 parts epoxy-modified waterborne acrylic resin, 5 parts nano silica, 8 parts modified graphene, 10 parts diethylenetriamine, 6 parts phthalic anhydride, 2 parts silane coupling agent KH550, and 60 parts ethylene glycol diglycidyl ether. Step S1: Weigh the raw materials according to the weight parts, add epoxy resin, epoxy modified waterborne acrylic resin and reactive diluent to the mixer, stir at 50 rpm / min for 15 min, then add nano silica, modified graphene and coupling agent, stir at 80 rpm / min for 20 min, and finally add diethylenetriamine and phthalic anhydride, stir at 100 rpm / min for 5 min to obtain the corrosion resistant coating; Step S2: Using 6061 aluminum alloy (10mm×10mm×2mm) as the base material, the aluminum alloy sample was polished with 2000# SiC sandpaper and cleaned with 99.99% alcohol. After cleaning, the aluminum alloy was placed in a 60wt% phosphoric acid alcohol solution for electrochemical polishing at 20A / dm. 2 ,20min, with aluminum alloy as the anode and stainless steel plate as the cathode, the pretreated aluminum alloy is obtained; Step S3: Use a spin coater to uniformly coat the pretreated aluminum alloy surface with a corrosion-resistant coating, and then place it at 80°C to cure it into a film, thus obtaining a graphene-based aluminum alloy surface coating.

[0013] Example 2: Modified graphene was prepared by the following steps: Step A1: Mix graphene, sodium dodecyl sulfate and water evenly, and then sonicate at 600W for 3 hours to obtain graphene dispersion. The ratio of graphene, sodium dodecyl sulfate and water is 1g:3g:100mL. Step A2: Nickel nitrate hexahydrate, cobalt nitrate hexahydrate, and terephthalic acid are stirred evenly in a mixture of N,N-dimethylformamide, ethanol, and water. Then, graphene dispersion is added and stirred for 30 minutes. The mixture is then transferred to a polytetrafluoroethylene reactor and hydrothermally reacted at 140°C for 30 hours. After filtration, washing, and vacuum drying, GR@Co / Ni-MOF is obtained. The ratio of nickel nitrate hexahydrate, cobalt nitrate hexahydrate, terephthalic acid, N,N-dimethylformamide, ethanol, water, and graphene dispersion is 0.007 mol: 0.01 mol: 0.015 mol: 50 mL: 5 mL: 5 mL: 7 mL. Step A3: Disperse benzotriazole evenly in acetone, add GR@Co / Ni-MOF and stir at room temperature for 2 hours, evacuate to vacuum for 30 minutes, and then ventilate to atmospheric pressure for 15 minutes. Repeat the above vacuuming and atmospheric pressure venting steps three times. Wash and dry to obtain modified graphene. The ratio of benzotriazole, acetone and GR@Co / Ni-MOF is 2g:100mL:0.2g.

[0014] A method for preparing a graphene-based aluminum alloy surface coating includes the following steps: 60 parts epoxy resin, 20 parts epoxy-modified waterborne acrylic resin, 7 parts nano silica, 10 parts modified graphene, 15 parts diethylenetriamine, 4 parts phthalic anhydride, 3 parts silane coupling agent KH550, and 80 parts ethylene glycol diglycidyl ether. Step S1: Weigh the raw materials according to the weight parts, add epoxy resin, epoxy modified waterborne acrylic resin and reactive diluent to the mixer, stir at 60 rpm / min for 20 min, then add nano silica, modified graphene and coupling agent, stir at 80 rpm / min for 30 min, and finally add diethylenetriamine and phthalic anhydride, stir at 100 rpm / min for 10 min to obtain the corrosion resistant coating. Step S2: Using 6061 aluminum alloy (10mm×10mm×2mm) as the base material, the aluminum alloy sample was polished with 2000# SiC sandpaper and cleaned with 99.99% alcohol. After cleaning, the aluminum alloy was placed in a 60wt% phosphoric acid alcohol solution for electrochemical polishing at 20A / dm. 2 ,20min, with aluminum alloy as the anode and stainless steel plate as the cathode, the pretreated aluminum alloy is obtained; Step S3: Use a spin coater to uniformly coat the pretreated aluminum alloy surface with a corrosion-resistant coating, and then place it at 90°C to cure it into a film, thus obtaining a graphene-based aluminum alloy surface coating.

[0015] Example 3: Modified graphene was prepared by the following steps: Step A1: Mix graphene, sodium dodecyl sulfate and water evenly, and then sonicate at 650W for 3 hours to obtain graphene dispersion. The ratio of graphene, sodium dodecyl sulfate and water is 1g:4g:100mL. Step A2: Nickel nitrate hexahydrate, cobalt nitrate hexahydrate, and terephthalic acid are stirred evenly in a mixture of N,N-dimethylformamide, ethanol, and water. Then, graphene dispersion is added and stirred for 30 minutes. The mixture is then transferred to a polytetrafluoroethylene reactor and hydrothermally reacted at 150°C for 36 hours. After filtration, washing, and vacuum drying, GR@Co / Ni-MOF is obtained. The ratio of nickel nitrate hexahydrate, cobalt nitrate hexahydrate, terephthalic acid, N,N-dimethylformamide, ethanol, water, and graphene dispersion is 0.009 mol:0.01 mol:0.018 mol:50 mL:5 mL:5 mL:9 mL. Step A3: Disperse benzotriazole evenly in acetone, add GR@Co / Ni-MOF and stir at room temperature for 2 hours, evacuate to vacuum for 30 minutes, and then ventilate to atmospheric pressure for 15 minutes. Repeat the above vacuuming and atmospheric pressure venting steps three times. Wash and dry to obtain modified graphene. The ratio of benzotriazole, acetone and GR@Co / Ni-MOF is 2.5g:100mL:0.4g.

[0016] A method for preparing a graphene-based aluminum alloy surface coating includes the following steps: 9 parts of modified graphene, 12 parts of diethylenetriamine, 15 parts of phthalic anhydride, 8 parts of phthalic anhydride, 4 parts of silane coupling agent KH570, and 90 parts of ethylene glycol diglycidyl ether. Step S1: Weigh the raw materials according to the weight parts, add epoxy resin, epoxy modified waterborne acrylic resin and reactive diluent to the mixer, stir at 70 rpm / min for 25 min, then add nano silica, modified graphene and coupling agent, stir at 80 rpm / min for 30 min, and finally add diethylenetriamine and phthalic anhydride, stir at 100 rpm / min for 10 min to obtain the corrosion resistant coating. Step S2: Using 6061 aluminum alloy (10mm×10mm×2mm) as the base material, the aluminum alloy sample was polished with 2000# SiC sandpaper and cleaned with 99.99% alcohol. After cleaning, the aluminum alloy was placed in a 60wt% phosphoric acid alcohol solution for electrochemical polishing at 20A / dm. 2 ,20min, with aluminum alloy as the anode and stainless steel plate as the cathode, the pretreated aluminum alloy is obtained; Step S3: Use a spin coater to uniformly coat the pretreated aluminum alloy surface with a corrosion-resistant coating, and then place it at 100°C to cure it into a film, thus obtaining the graphene-based aluminum alloy surface coating.

[0017] Example 4: Modified graphene was prepared by the following steps: Step A1: Mix graphene, sodium dodecyl sulfate and water evenly, and then sonicate at 700W for 3 hours to obtain graphene dispersion. The ratio of graphene, sodium dodecyl sulfate and water is 1g:5.5g:100mL. Step A2: Nickel nitrate hexahydrate, cobalt nitrate hexahydrate, and terephthalic acid are stirred evenly in a mixture of N,N-dimethylformamide, ethanol, and water. Then, graphene dispersion is added and stirred for 30 minutes. The mixture is then transferred to a polytetrafluoroethylene reactor and hydrothermally reacted at 150°C for 48 hours. After filtration, washing, and vacuum drying, GR@Co / Ni-MOF is obtained. The ratio of nickel nitrate hexahydrate, cobalt nitrate hexahydrate, terephthalic acid, N,N-dimethylformamide, ethanol, water, and graphene dispersion is 0.01 mol: 0.01 mol: 0.02 mol: 50 mL: 5 mL: 5 mL: 10 mL. Step A3: Disperse benzotriazole evenly in acetone, add GR@Co / Ni-MOF and stir at room temperature for 2 hours, evacuate under vacuum for 30 minutes, and then ventilate under atmospheric pressure for 15 minutes. Repeat the above vacuuming and atmospheric ventilating steps three times. Wash and dry to obtain modified graphene. The ratio of benzotriazole, acetone and GR@Co / Ni-MOF is 3g:100mL:0.5g.

[0018] A method for preparing a graphene-based aluminum alloy surface coating includes the following steps: 70 parts epoxy resin, 25 parts epoxy-modified waterborne acrylic resin, 10 parts nano silica, 15 parts modified graphene, 15 parts diethylenetriamine, 10 parts phthalic anhydride, 4 parts silane coupling agent KH550, and 100 parts ethylene glycol diglycidyl ether. Step S1: Weigh the raw materials according to the weight parts, add epoxy resin, epoxy modified waterborne acrylic resin and reactive diluent to the mixer, stir at 70 rpm / min for 25 min, then add nano silica, modified graphene and coupling agent, stir at 80 rpm / min for 30 min, and finally add diethylenetriamine and phthalic anhydride, stir at 100 rpm / min for 10 min to obtain the corrosion resistant coating. Step S2: Using 6061 aluminum alloy (10mm×10mm×2mm) as the base material, the aluminum alloy sample was polished with 2000# SiC sandpaper and cleaned with 99.99% alcohol. After cleaning, the aluminum alloy was placed in a 60wt% phosphoric acid alcohol solution for electrochemical polishing at 20A / dm. 2 ,20min, with aluminum alloy as the anode and stainless steel plate as the cathode, the pretreated aluminum alloy is obtained; Step S3: Use a spin coater to uniformly coat the pretreated aluminum alloy surface with a corrosion-resistant coating, and then place it at 100°C to cure it into a film, thus obtaining the graphene-based aluminum alloy surface coating.

[0019] Comparative Example 1: This comparative example is a coating for aluminum alloy surfaces. The difference from Example 4 is that graphene is used instead of modified graphene, while the rest are the same.

[0020] Comparative Example 2: This comparative example is a coating for aluminum alloy surfaces. The difference from Example 4 is that no modified graphene was added, but all other aspects are the same.

[0021] The corrosion resistance of the coatings on the aluminum alloy surfaces prepared in Examples 1-4 and Comparative Examples 1-2 was tested. The test method for acid corrosion resistance is as follows: 2 ml of 40 wt% sulfuric acid is dropped onto the surface of the sample and kept at 25 ℃ for 24 h. The blistering corrosion phenomenon on the surface of the film is then observed. The test method for resistance to alkaline corrosion is as follows: 2 mL of 0.1 mol / L standard concentration sodium hydroxide solution is dropped onto the surface of the sample, kept at 25℃ for 24 h, and the blistering corrosion phenomenon on the film surface is observed. The test method for salt corrosion resistance is as follows: drop 2 mL of 50 wt% sodium chloride solution onto the surface of the sample, keep it at 25 ℃ for 24 h, and observe the blistering corrosion phenomenon on the surface of the film layer. The test results are shown in Table 1: Table 1: Performance Test Results

[0022] As can be seen from Table 1, the graphene-based coating prepared by this invention has excellent acid, alkali and salt resistance on the aluminum alloy surface. Based on this, its application on the surface of aluminum alloy products has excellent corrosion resistance.

[0023] The above content is merely an example and illustration of the concept of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the scope defined by the inventive concept, they should all fall within the protection scope of the present invention.

Claims

1. A graphene-based aluminum alloy surface coating, characterized in that, The raw materials include the following parts by weight: 50-70 parts of bisphenol A type epoxy resin, 15-25 parts of epoxy modified waterborne acrylic resin, 5-10 parts of nano silica, 8-15 parts of modified graphene, 10-15 parts of diethylenetriamine, 4-10 parts of phthalic anhydride, 2-4 parts of coupling agent, and 60-100 parts of reactive diluent. The modified graphene is GR@Co / Ni-MOF supported on benzotriazole. The GR@Co / Ni-MOF is synthesized in situ on the graphene surface using nickel nitrate hexahydrate, cobalt nitrate hexahydrate, and terephthalic acid as raw materials. The modified graphene is prepared by the following steps: Step A1: Mix graphene, sodium dodecyl sulfate and water evenly, and then sonicate at 600-700W for 3 hours to obtain graphene dispersion. Step A2: Nickel nitrate hexahydrate, cobalt nitrate hexahydrate, and terephthalic acid are stirred evenly in a mixture of N,N-dimethylformamide, ethanol, and water. Then, graphene dispersion is added and stirred for 30 minutes. The mixture is then transferred to a polytetrafluoroethylene reactor and hydrothermally reacted at 130-150℃ for 24-48 hours. After filtration, washing, and vacuum drying, GR@Co / Ni-MOF is obtained. Step A3: Disperse benzotriazole evenly in acetone, add GR@Co / Ni-MOF and stir at room temperature for 2 hours, evacuate to vacuum for 30 minutes, and then ventilate to atmospheric pressure for 15 minutes. Repeat the above vacuuming and atmospheric pressure venting steps three times, wash and dry to obtain modified graphene.

2. The graphene-based aluminum alloy surface coating according to claim 1, characterized in that, In step A1, the ratio of graphene, sodium dodecyl sulfate, and water is 1g:2.5-5.5g:100mL.

3. The graphene-based aluminum alloy surface coating according to claim 1, characterized in that, In step A2, the ratio of nickel nitrate hexahydrate, cobalt nitrate hexahydrate, terephthalic acid, N,N-dimethylformamide, ethanol, water, and graphene dispersion is 0.005-0.01 mol: 0.01 mol: 0.015-0.02 mol: 50 mL: 5 mL: 5 mL: 5-10 mL.

4. The graphene-based aluminum alloy surface coating according to claim 1, characterized in that, In step A3, the ratio of benzotriazole, acetone and GR@Co / Ni-MOF is 1-3g:100mL:0.1-0.5g.

5. The graphene-based aluminum alloy surface coating according to claim 1, characterized in that, The active diluent is ethylene glycol diglycidyl ether.

6. The graphene-based aluminum alloy surface coating according to claim 1, characterized in that, The coupling agent is one of the silane coupling agents KH550, KH560 or KH570.

7. A method for preparing a graphene-based aluminum alloy surface coating according to any one of claims 1-6, characterized in that, Includes the following steps: Step S1: Weigh the raw materials according to the weight parts, add epoxy resin, epoxy modified waterborne acrylic resin and reactive diluent to the mixer, stir at 50-70 rpm for 15-25 min, then add nano silica, modified graphene and coupling agent, stir at 80 rpm for 20-30 min, and finally add diethylenetriamine and phthalic anhydride, stir at 100 rpm for 5-10 min to obtain the corrosion resistant coating. Step S2: Using 6061 aluminum alloy as the base material, the aluminum alloy sample is polished with 2000# SiC sandpaper and cleaned with 99.99% alcohol. After cleaning, the aluminum alloy is placed in a 60wt% phosphoric acid alcohol solution for electrochemical polishing to obtain the pretreated aluminum alloy. Step S3: Use a spin coater to uniformly coat the pretreated aluminum alloy surface with a corrosion-resistant coating, and then place it at 80-100℃ to cure it into a film, thus obtaining the graphene-based aluminum alloy surface coating.

8. The method for preparing a graphene-based aluminum alloy surface coating according to claim 7, characterized in that, The electrochemical polishing conditions in step S2 are: 20 A / dm 2 ,20min, with aluminum alloy as the anode and stainless steel plate as the cathode.

9. An application of the graphene-based aluminum alloy surface coating according to any one of claims 1-6, characterized in that, Used on the surface of aluminum alloy products.

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