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A Magnesium Alloy, A Piston Manufactured by Said Magnesium Alloy and a Method for Manufacturing Said Piston

20220154315 · 2022-05-19

    Inventors

    Cpc classification

    International classification

    Abstract

    A magnesium alloy containing: Al: 0.2-1.6 wt. % Zn: 0.2-0.8 wt. % 5 Mn: 0.1-0.5 wt. % Zr 0-0.5 wt. % La: 1-3.5 wt. % Y: 0.05-3.5 wt. % Ce: 0-2 wt. % 10 Nd: 0-2 wt. % Gd: 0-3 wt. % Pr: 0-0.5 wt. % Be: 0-20 ppm the balance being Mg and incidental elements.

    Claims

    1. A magnesium alloy containing: Al: 0.2-1.6 wt. % Zn: 0.2-0.8 wt. % Mn: 0.1-0.5 wt. % Zr 0-0.5 wt. % La: 1-3.5 wt. % Y: 0.05-3.5 wt. % Ce: 0-2 wt. % Nd: 0-2 wt. % Gd: 0-3 wt. % Pr: 0-0.5 wt. % Be: 0-20 ppm the balance being Mg and incidental elements in an amount of 0-3 wt. %.

    2. The magnesium alloy according to claim 1 wherein the amount of Al is 0.3-0.8 wt. %.

    3. The magnesium alloy according to claim 1, wherein the amount of Zn is 0.3-0.6 wt. %.

    4. The magnesium alloy according to claim 1, wherein the amount of La is 1.5-2 wt. %.

    5. The magnesium alloy according to claim 1, wherein the amount of Y is 0.05-0.2 wt. %.

    6. The magnesium alloy according to claim 1, wherein the amount of Ce is 0.5-1.5 wt. %.

    7. The magnesium alloy according to claim 1, wherein the amount of Nd is 0.5-1.5 wt. %.

    8. The magnesium alloy according to claim 1, wherein the amount of Gd is 1-3 wt. %.

    9. The magnesium alloy according to claim 1, wherein the amount of Pr is 0-0.3 wt %.

    10. The magnesium alloy according to claim 1, wherein the amount of Al is 0.2-1.5 wt %.

    11. The magnesium alloy according to claim 10, wherein the amount of Y is 1-3.5 wt. %, and wherein the amount of La is 1.5-3.5 wt. %.

    12. (canceled)

    13. The magnesium alloy according to claim 1, wherein a sum of amounts of La and at least one element selected from the group of Y, Ce, Nd, Gd, Pr is 5-6 wt. %.

    14. The magnesium alloy according to claim 1, wherein the alloy contains: 0.3-0.8 wt. % Al, 0.3-0.6 wt. % Zn, 0.15-0.3 wt. % Mn, 0-0.5 wt. % Zr, 1.5-2 wt. % La, 0.05-0.15 wt. % Y, 0.5-1 wt. % Ce, 0.8-1.2 wt. % Nd, 1.4-1.6 wt. % Gd, 0-0.3 wt. % Pr, 0-20 ppm Be.

    15. The magnesium alloy according to claim 1, wherein the alloy contains: 0.2-1.5 wt. % Al, 0.2-0.6 wt. % Zn, 0.1-0.4 wt. % Mn, 0-0.5 wt. % Zr, 1.5-3.5 wt. % La, 0-1 wt. % Ce, 0-0.5 wt. % Nd, 0-0.5 wt. % Gd, 1.5-3 wt. % Y, 0-0.3 wt. % Pr, 0-20 ppm Be.

    16. The magnesium alloy according to claim 1, wherein the amount of Mg is ≤93.5 wt. %.

    17. A piston for a combustion engine, the piston being manufactured from a magnesium alloy comprising: Al: 0.2-1.6 wt. % Zn: 0.2-0.8 wt. % Mn: 0.1-0.5 wt. % Zr 0-0.5 wt. % La: 1-3.5 wt. % Y: 0.05-3.5 wt. % Ce: 0-2 wt. % Nd: 0-2 wt. % Gd: 0-3 wt. % Pr: 0-0.5 wt. % Be: 0-20 ppm the balance being Mg and incidental elements in an amount of 0-3 wt. %.

    18. The piston according to claim 17, wherein the piston is configured for a two-stroke engine of a hand-held power tool, and wherein the piston comprises an oxidized surface layer.

    19. (canceled)

    20. A method for manufacturing a piston for a combustion engine comprising the steps: providing a magnesium alloy according to claim 1; melting the magnesium alloy; casting the magnesium alloy into a mold cavity defining the shape of a piston; solidification of the magnesium alloy in the mold cavity; removing the solidified piston from the mold cavity.

    21. The method according to claim 20, wherein the step of casting the magnesium alloy is made by High Pressure Die Casting.

    22. The method according to claim 20 further comprising a step of providing an oxide layer on the surface of the piston by Plasma Electrolytic Oxidation.

    Description

    BRIEF DESCRIPTION OF THE DRAWINGS

    [0055] FIG. 1: A schematic drawing of a piston for a combustion engine according to the present disclosure.

    [0056] FIG. 2: A flowchart showing schematically the steps of a method according to the present disclosure.

    DETAILED DESCRIPTION OF EMBODIMENTS

    [0057] FIG. 1 shows schematically a piston 1 according to the present disclosure for a combustion engine. Here exemplified as a piston for a two-stroke engine for a hand-held motor tool. The piston 1, comprises, i.e. is manufactured from, the magnesium alloy according to the first aspect of the present disclosure. The piston 1 is provided with a coating 2 of magnesium oxide. The coating 2 may be provided on the entire outer surface of the piston 1, as shown in FIG. 2. However, it is possible to provide the coating 2 on only a portion of the outer surface of the piston 1.

    [0058] The piston may be manufactured by the following method. The steps of the method may be followed in FIG. 2.

    [0059] Thus, in a first step 1000 of the method, a magnesium alloy according to the present disclosure is provided. Typically, the magnesium alloy is provided in form of pre-manufactured solid pieces such as ingots. In a second step 2000, the magnesium alloy is melted such that it assumes a liquid state. Melting is performed by heating the magnesium alloy above its melting point. Typically the magnesium alloy may thereby be heated to a temperature of 720° C. or above. In a third step 3000, the molten magnesium alloy is cast, i.e. poured into a mold having a mold cavity which defines the shape of a piston for a combustion engine. For example, the mold cavity defines the shape of a piston for a two-stroke combustion engine. In a fourth step 4000 the molten magnesium alloy is allowed to solidify for a predetermined time in the mold cavity. The solidification time depends on dimensions of the piston and casting conditions and may be determined in advance by e.g. practical trials. In a fifth step 5000, the piston is removed, from the mold cavity. The mold may thereby comprise two mold halves which may are movable away from each other to allow access to the mold cavity and the solidified piston.

    [0060] Casting of the piston is preferably made by High Pressure Die Casting (HPDC). In this process, molten metal is injected under velocity and high pressure into a forming cavity that is formed between two mold halves that are clamped together. The HPDC process allows for fast production of components with high dimensional accuracy due to that the forming cavity is rapidly filled with molten metal.

    [0061] The steps of melting of the magnesium alloy and the step of removing the solidified piston may be comprised in the High Pressure Die Casting equipment.

    [0062] After removal of the solidified piston, in an optional sixth step 6000, the piston may be subjected to a machining operation, such a drilling and or turning into final shape.

    [0063] Finally, the piston may be subjected to an optional seventh step 7000 of providing a coating on the surface of the piston. The coating is preferably a coating of magnesium oxide and may be achieved by Plasma Electrolytic Oxidation (PEO), which is a known electrochemical surface treatment process for generating oxide coatings on metals, such as magnesium. The Plasma Electrolytic Oxidation process achieves a hard and continuous oxide coating which offers protection against wear, corrosion and heat. An advantage of PEO is that the coating is a chemical conversion of the substrate metal into its oxide, and the coating therefore grows both inwards and outwards from the original metal surface. Because it grows inward into the substrate, it has excellent adhesion to the substrate metal.

    [0064] It is appreciated that the piston may have any suitable dimensions for its intended application.

    [0065] It is further appreciated the piston may be configured for four-stroke engines.

    [0066] Moreover, casting of the magnesium alloy may be achieved by other suitable casting processes. For example, sand casting, low-pressure die-casting, semi-solid metal processing or permanent mold gravity die-casting.