Oxidation-Resistant Bronze-PTFE Composition for Uniform Sintered Color

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Solution Overview

Problem

Bronze-polytetrafluoroethylene compounds often exhibit dark streaks and edge zone oxidation during sintering due to insufficient oxygen removal, leading to non-uniform color and increased waste, raw material consumption, and production costs, especially in the automobile industry.

Innovation Solution

The use of bronze particles with a specific elemental composition (10-30% Sn, 2-20% Zn, and 0.1-5% Al or 0.01-0.4% P, with the remainder being Cu and inevitable impurities, eliminates the need for surface coatings, providing inherent oxidation resistance and preventing dark streaks and edge zone oxidation during sintering.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional bronze powder is used without surface coating, then the production process is simpler and more efficient, but dark streaks and edge zone oxidation occur during sintering resulting in non-uniform color

Engineering Contradiction:
Improveproduction efficiencyVSAvoidcolor uniformity
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent changes the chemical composition parameters of the bronze powder by adding specific elements (Al: 0.01-5 mass%, Si: 0.01-5 mass%, P: 0.01-0.5 mass%) to conventional bronze (Cu-Sn alloy). This compositional modification enables the bronze to form protective oxide layers during sintering, preventing edge zone oxidation and dark streak formation without requiring surface coatings, thus maintaining production efficiency while achieving uniform color appearance.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite bronze material by combining Cu-Sn alloy with additional elements (Al, Si, P) that provide oxidation resistance. This composite bronze powder exhibits both the desired mechanical properties and color uniformity during sintering, eliminating the need for separate surface coating processes while preventing harmful oxidation effects.

Inventive Principle:
Principle #40Composite materials

2Reliability

If high pressure treatment is applied to remove oxygen, then oxidation during sintering is reduced, but production time and energy consumption increase

Engineering Contradiction:
Improveoxidation resistanceVSAvoidenergy consumption
Core Design Contradiction:
ReliabilityVSUse of energy by stationary object

Solution Approach 1:

The modified bronze powder is formulated to be self-protecting against oxidation through its inherent composition. The added elements (Al, Si, P) automatically form protective oxide layers on the bronze particle surfaces during sintering, eliminating the need for external high pressure treatment to remove oxygen. This self-service mechanism reduces energy consumption while maintaining reliable oxidation resistance.

Inventive Principle:
Principle #25Self-service

3Reliability

If surface coatings are applied to bronze powder, then oxidation resistance is improved, but manufacturing complexity and cost increase

Engineering Contradiction:
Improveoxidation resistanceVSAvoidprocess complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the oxidation protection function from the separate surface coating process and integrates it directly into the bronze powder composition itself. By incorporating Al, Si, and P elements into the bronze alloy, the oxidation resistance is built-in at the material level, eliminating the need for additional surface coating equipment and process steps, thus reducing manufacturing complexity while maintaining reliability.

Inventive Principle:
Principle #2Taking out (Extraction)

4Manufacturing precision

If edge zones with oxidation are removed by peeling and cutting, then product quality is improved, but raw material consumption and waste increase

Engineering Contradiction:
Improveproduct qualityVSAvoidraw material waste
Core Design Contradiction:
Manufacturing precisionVSLoss of substance

Solution Approach 1:

The modified bronze powder composition prevents edge zone oxidation before it occurs during sintering. The Al, Si, and P elements proactively form protective layers that stop oxidation at the edges, eliminating the need for subsequent peeling and cutting operations. This preliminary anti-action ensures complete utilization of raw materials without waste while maintaining high product quality.

Inventive Principle:
Principle #9Preliminary anti-action

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 bronze-polytetrafluoroethylene compounds produced with these oxidation-resistant bronze particles have a uniform appearance and consistent color, reducing waste and production costs while simplifying the manufacturing process by eliminating the need for additional surface coatings and high-pressure oxygen removal.

Implementation Method 1

the bronze particles have an elemental composition consisting of: Sn in an amount of from 10 to 30 mass%; Zn in an amount of from 2 to 20 mass%; and one of the following elements: Al in an amount of from 0.1 to 5 mass%; or P in an amount of from 0.01 to 0.4 mass%, with the remainder consisting of Cu and inevitable impurities, wherein the bronze particles have no surface coating

Methodology Applied
Scientific EffectOxidation resistance: Oxidation

Implementation Method 2

followed by sintering the green body, e.g. in air circulation ovens or in the course of ram extrusion

Methodology Applied
Scientific EffectSintering: Sintering

Data Source

PatentEP3694661B1Bronze-polytetrafluoroethylene compounds based on an oxidation-resistant bronze powder, production method of said compounds, bronze powder and its use
Publication Date: 2022.06.15 SCHLENK METALLIC PIGMENTS GMBH
  • EP3694661B1 patent drawingFigure 1

AI summary

The present invention relates to a bronze-polytetrafluoroethylene compound based on an oxidation-resistant bronze powder, and to a method for producing the bronze-polytetrafluoroethylene compound. In another aspect, the present invention relates to an oxidation-resistant bronze powder for use in polytetrafluoroethyiene compounds.