Precoated sand material applicable to laser sintering of magnesium alloy, and preparation method thereof

A technology of laser sintering and coated sand, which is applied in metal processing equipment, manufacturing tools, casting molding equipment, etc.

Inactive Publication Date: 2014-02-05
NANCHANG HANGKONG UNIVERSITY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the SLS coated sand mold / sand core has a large amount of organic matter and oxides in its constituent materials and bonding materials, which makes the high active reaction between magnesium and SLS coated sand mold / sand core, especially the magnesium alloy pouring temperature is too high When using a simple flame retardant coating layer, it is difficult to prevent the interface reaction or local combustion between the magnesium alloy and the SLS coated sand mold / sand core, which will cause surface ablation of the casting, and the formation of micropores, holes and other defects, which will deteriorate the magnesium alloy casting. surface quality and mechanical properties
Especially in the integrated manufacturing of SLS coated sand molds / sand cores, in some closed and nearly closed complex inner cavities (for example: some inner cavities with complex flow channels, three-dimensional crossings and small distances between multi-channel variable cross-section slender Complex structural parts such as pipes) are difficult to spray paint, which greatly limits the engineering application of magnesium alloy SLS coated sand casting

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0042] B. Mix boric acid powder and pyrite powder evenly in a ratio of 1:20 to obtain a composite flame retardant;

[0043] C, pulverizing the solid thermoplastic phenolic resin into a particle size of 50 μm, uniform phenolic resin powder;

[0044] D. Sieve spherical or very spherical pearl sand with a diagonal coefficient ≤ 1.1 to obtain 100 / 200 mesh pearl fine sand with a main content of ≥ 90%;

[0045] E. The phenolic resin coated sand is prepared by the conventional thermal coating method, wherein: 1000g of the above pearl fine sand, 12g of phenolic resin powder with a particle size of 50μm (the mass fraction of the pearl sand is 1.2%), γ ―Aminopropyltriethoxysilane 0.12g (addition amount accounted for 1% of the mass fraction of phenolic resin powder, made into an aqueous solution with a mass fraction of 10%), hexamethylenetetramine 1.44g (addition amount accounted for phenolic resin powder The mass fraction of the powder is 12%, and it is made into an aqueous solution wi...

Embodiment 2

[0050] B. Mix boric acid powder and pyrite powder evenly in a ratio of 1:30 to obtain a composite flame retardant;

[0051] C, pulverizing the solid thermoplastic phenolic resin into a particle size of 30 μm, uniform phenolic resin powder;

[0052] D. Sieve the raw sand;

[0053] E. The screened raw sand, phenolic resin powder, coupling agent, and curing agent are coated with conventional phenolic resin thermal method to obtain phenolic resin coated sand, and then in the prepared phenolic resin coated sand Add flame retardant, and mix by 3.5wt% of phenolic resin coated sand mass fraction;

[0054] F. Sieve and pack the phenolic resin coated sand to obtain a finished product of coated sand material suitable for casting magnesium alloy by laser sintering for selective area forming.

[0055] Example 3:

[0056] A method for preparing a coated sand material suitable for laser sintering of magnesium alloys, the specific steps are as follows:

Embodiment 3

[0058] B. Mix carbon powder and pyrite powder evenly in a ratio of 1:10 to obtain a composite flame retardant;

[0059] C, pulverizing the solid thermoplastic phenolic resin into a particle size of 40 μm, uniform phenolic resin powder;

[0060] D. Sieve spherical or very spherical pearl sand with a diagonal coefficient ≤ 1.1 to obtain 100 / 200 mesh pearl fine sand with a main content of ≥ 90%;

[0061] E. Prepare phenolic resin coated sand by conventional thermal coating method, wherein: 2000g of the above pearl fine sand, 24g of phenolic resin powder with a particle size of 40μm (the amount added is 1.2% of the mass fraction of pearl sand), γ ―Aminopropyltriethoxysilane 0.24g (addition amount accounted for 1% of the mass fraction of phenolic resin powder, made into an aqueous solution with a mass fraction of 10%), hexamethylenetetramine 2.88g (addition amount accounted for phenolic resin powder The mass fraction of the powder is 12%, and it is made into an aqueous solution wi...

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Abstract

The invention discloses a preparation method for a precoated sand material applicable to the laser sintering of a magnesium alloy. The precoated sand material comprises evenly mixed crude sand, an organic binder, a coupling agent, a curing agent and a flame retardant, wherein the flame retardant is a mixture of any two or three of boric acid powder, carbon powder and pyrite powder. By adding the composite flame retardant, the defects of surface ablation and formed holes, micropores and the like when in pouring a magnesium alloy can be greatly reduced; in addition, the composite flame retardant added in the precoated sand solves the problem that a single flame retardant can greatly reduce the strength of an initial precoated sand laser-sintered part blank. According to the preparation method, not only can the magnesium alloy flame retardance problem of an SLS precoated sand mold sand core be solved, but also the strength of the initial laser-sintered molding part blanks can be guaranteed, the precoated sand material can be directly applied to pouring of a magnesium alloy, especially to high-temperature pouring of the magnesium alloy, and has great advantages on the fast integral precise forming aspects of especially complicated inner cavity, and integrated sand mold sand core.

Description

technical field [0001] The invention belongs to the technical field of casting, and in particular relates to a coated sand material for laser sintering suitable for magnesium alloys under high-temperature pouring conditions and a preparation method thereof. Background technique [0002] Magnesium metal is abundant on the earth, and magnesium alloy is currently one of the lightest metal structural materials, which can greatly reduce the weight of structural parts in engineering applications. Compared with other metal materials, magnesium alloy has specific strength and specific stiffness High, good thermal conductivity, stable size, good shock and noise reduction ability and electromagnetic shielding performance, and easy to recycle; in addition, it also has good casting performance and cutting performance. At present, magnesium alloy, as a typical lightweight engineering material, has been widely used in the fields of aerospace, national defense, automobile and electronic co...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B22C1/00B22C1/02B22F3/105
CPCY02P10/25
Inventor 徐志锋李偲偲张永才蔡长春熊博文余欢
Owner NANCHANG HANGKONG UNIVERSITY
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