Composite Nozzle for Continuous Casting of Magnesium Alloy
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Solution Overview
Problem
Continuous casting nozzles face issues with wear and deterioration due to contact with hot molten magnesium or magnesium alloys, leading to non-uniform metal flow and surface defects in cast materials, as well as the formation of gaps between the nozzle and moving mold, causing local disturbances and surface defects.
Innovation Solution
A composite material is developed comprising a porous body with high mechanical strength and low reactivity, combined with a filler having low wettability, such as nitrides, carbides, or carbon, which reduces contact with molten metal and prevents penetration, oxidation, and deformation, while a coating layer with similar components enhances repelling properties and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a nozzle is made from a single material to prevent reaction with molten magnesium, then chemical stability is improved, but mechanical strength and wear resistance deteriorate due to the requirements of low reactivity
Solution Approach 1:
The nozzle is constructed as a composite material consisting of a porous base material (such as carbon or carbon-containing composite) combined with a filler material (such as alumina, magnesia, or spinel) having specific properties. This composite structure allows the nozzle to simultaneously achieve chemical stability against molten magnesium from the filler material and mechanical strength from the porous base material, resolving the contradiction between chemical stability and mechanical strength.
2Ease of manufacture
If the nozzle structure is simplified to reduce manufacturing cost, then ease of manufacture is improved, but gap formation between nozzle and moving mold worsens leading to surface defects
Solution Approach 1:
The nozzle tip is designed with a specific geometric structure including a tapered portion and a gap prevention structure that locally controls the gap between the nozzle and moving mold. This local structural optimization ensures precise gap control at the critical discharge region while maintaining overall manufacturing simplicity, resolving the contradiction between ease of manufacture and manufacturing precision.
3Loss of substance
If the nozzle is designed with thin walls to reduce material consumption, then loss of substance is improved, but mechanical strength and durability worsen due to wear and deterioration
Solution Approach 1:
The nozzle body is constructed using a porous material (such as carbon felt or porous carbon composite) that provides high surface area to volume ratio and excellent thermal shock resistance. This porous structure allows the nozzle to maintain mechanical strength and durability even with thin walls, while also providing good chemical stability against molten magnesium, thus resolving the contradiction between material consumption and nozzle durability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The composite material effectively suppresses wear and deterioration, maintains uniform molten metal flow, and produces cast materials with excellent surface quality over extended periods, reducing defects and ensuring stable casting operations.
Implementation Method 1
a filler which has low wettability with the molten metal compared to the porous body
Implementation Method 2
oxidation by heat of the molten metal and penetration of the molten metal
Data Source
Figure 1(A)~1(B)
AI summary
Provided is a composite material suitable for forming a part for continuous casting capable of producing cast materials of excellent surface quality for a long period of time and with which a molten metal is inhibited from flowing into a gap between a nozzle and a moving mold. A composite material (nozzle 1) includes a porous body 2 having a large number of pores and a filler incorporated in at least part of a portion that comes into contact with the molten metal, the portion being part of a surface portion of the porous body. The filler incorporated in the porous body 2 is at least one selected from a nitride, a carbide, and carbon.