Si-Coated Pure Copper Powder for Stable EB Additive Manufacturing

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Solution Overview

Problem

In additive manufacturing using the electron beam method, pure copper powder tends to partially sinter during preheating, leading to difficulties in escaping from molded object holes and causing a loss of vacuum due to carbon contamination, which destabilizes molding conditions.

Innovation Solution

A production method involving a pure copper powder with a Si coating, where the Si adhesion amount is between 5 to 200 wtppm, C adhesion amount is 15 wtppm or more, and a weight ratio C/Si of 3 or less, with preheating temperatures between 400°C and 800°C, and specific electron beam molding conditions to suppress sintering and maintain vacuum integrity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If pure copper powder is preheated in EB-based additive manufacturing, then charge-up problem is resolved and electron beam scanning becomes feasible, but partial sintering occurs making it difficult for powder to escape from molded object holes

Engineering Contradiction:

Improvecharge-up preventionVSAvoidpowder escape ability

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

An organic coating is introduced as an intermediary substance between the pure copper powder particles. This coating layer prevents direct contact and bonding between copper particles during preheating, thereby suppressing sintering while allowing the powder to maintain its ability to escape from molded object holes after the additive manufacturing process is complete.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The preheating temperature is optimized to a specific range that is sufficient to prevent charge-up and enable electron beam scanning, but controlled to remain below the threshold that causes excessive sintering. This parameter optimization resolves the contradiction by finding the optimal operating point that satisfies both requirements.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If organic coating is formed on metal powder surface using silane coupling agent, then partial sintering is suppressed, but carbon contamination occurs causing loss of vacuum during molding

Engineering Contradiction:

Improvesintering suppressionVSAvoidcarbon contamination

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The composition parameters of the organic coating are precisely controlled, specifically limiting the carbon content and optimizing the Si/C ratio. By adjusting these chemical parameters, the coating maintains its sintering suppression function while minimizing carbon contamination that would cause vacuum loss during molding.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The organic coating is designed as a composite material with specific compositional ratios of Si and C elements. This composite structure provides both the sintering suppression capability (through Si content) and minimizes harmful carbon contamination (through controlled C content and Si/C ratio), resolving the contradiction between protective function and harmful byproduct generation.

Inventive Principle:

Principle #40Composite materials

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

This method effectively prevents partial sintering of the copper powder and maintains vacuum stability during the molding process, enabling efficient electron beam melting and producing additive manufactured objects with favorable surface conditions.

Implementation Method 1

melting the metal powder layer by scanning the metal powder layer with an electron beam or a laser beam

Methodology Applied

Scientific EffectElectron beam: Electron Beam

Implementation Method 2

Transform Electromagnetic Energy to Thermal Energy

Methodology Applied

Scientific EffectElectromagnetic energy to thermal energy conversion:

Implementation Method 3

the metal powder is preheated and adjacent metal powders are necked to create a conductive path

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 4

solidifying the metal powder layer

Methodology Applied

Scientific EffectSolidification: Freezing

Data Source

PatentUS11872647B2Production method of additive manufactured object using pure copper powder having Si coating

Publication Date: 2024.01.16 JX NIPPON MINING & METALS CORP

AI summary

A production method of an additive manufactured object is provided. The method is an EB-based additive manufacturing method of spreading a pure copper powder, preheating the pure copper powder and thereafter partially melting the pure copper powder by scanning the pure copper powder with an electron beam, solidifying the pure copper powder to form a first layer, newly spreading a pure copper powder on the first layer, preheating the pure copper powder and thereafter partially melting the pure copper powder by scanning the pure copper powder with an electron beam, solidifying the pure copper powder to form a second layer, and repeating the foregoing process to add layers. The pure copper powder is a pure copper powder with a Si coating formed thereon, and the preheating temperature is set to be 400° C. or higher and less than 800° C.