Iron-Chromium Wire Arc Spraying for Diesel Corrosion Resistance
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Solution Overview
Problem
Existing wire arc spraying methods for producing corrosion-resistant and hard layers on engine components are costly due to the need for additional hard material particles like boron carbide, which also complicates machinability, and commercial iron/carbon alloy layers tend to corrode.
Innovation Solution
A wire-form spraying material comprising an iron/chromium alloy with 12-20% Cr, where the layer achieves 10% Cr minimum, using nitrogen as a process gas for interstitial hardening and nitride formation, along with specific alloying constituents like sulfur and molybdenum sulfide to enhance machinability and reduce friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If boron carbide particles are added to increase layer hardness, then hardness is improved, but process costs increase and machinability deteriorates
Solution Approach 1:
The invention extracts and eliminates the need for additional hard material particles like boron carbide by achieving the desired layer hardness (400-850 HV 0.1) through optimized iron/chromium alloy composition (10-20% Cr, 0.7-1.2% C) and process parameters alone, thereby simplifying the material system and improving machinability
Solution Approach 2:
The invention changes the compositional parameters of the base alloy (specifically Cr content at 10-20% and C content at 0.7-1.2%) to achieve the target hardness range, replacing the need for particle reinforcement while maintaining cost-effectiveness and machinability
2Reliability
If chromium content is increased to improve corrosion resistance, then corrosion resistance is improved, but additional hard material particles are required to achieve adequate hardness
Solution Approach 1:
The invention merges the functions of corrosion resistance and hardness achievement into a single integrated solution by combining optimized chromium content (10-20%) with carbon content (0.7-1.2%) in the alloy, eliminating the need for separate particle reinforcement while achieving both ≥10% Cr in the layer and 400-850 HV 0.1 hardness
Solution Approach 2:
The invention creates a composite microstructure within the alloy system itself, where chromium provides corrosion resistance and carbon forms hard carbide phases in situ, achieving both protective and mechanical properties without external particle addition
3Strength
If additional hard material particles are supplied, then layer hardness is improved, but conveying system complexity increases
Solution Approach 1:
The invention extracts and removes the entire additional powder conveying system by achieving adequate layer hardness through wire-only feeding with optimized alloy composition, thereby eliminating independent powder conveying equipment and simplifying the overall system
Solution Approach 2:
The wire-form spraying material is designed to perform multiple functions simultaneously: providing the base matrix, achieving corrosion resistance through chromium, and achieving hardness through carbon content and alloying, eliminating the need for separate particle reinforcement systems
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 solution results in a dense, corrosion-resistant, and wear-resistant layer with reduced friction and porosity, improving machinability and maintaining high hardness without additional costly materials, while maintaining high corrosion resistance even in contact with diesel fuel with high sulfur content.
Implementation Method 1
an arc is generated between two wire-form spraying materials by applying a voltage. In the process, the wire tips melt off
Implementation Method 2
The use of nitrogen as process gas causes nitrogen to be introduced into the layer, which results firstly in additional strength by virtue of interstitial hardening
Implementation Method 3
secondly in the formation of wear-reducing and friction-reducing nitrides
Data Source
AI summary
A wire-like spray material (4) based on an iron for electric arc wire spraying and also a functional layer (2) which can be produced therewith on a substrate (1). The functional layer (2) has good corrosion resistance towards diesel fuel having a high sulphur content.