Sliding Surface Cobalt Alloy Coating for Low-Temperature Wear Resistance
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Solution Overview
Problem
Conventional wear-resistant coatings formed using cobalt alloys like Stellite via TIG welding fail to form lubricious oxides at temperatures below 600°C, leading to increased wear on sliding parts.
Innovation Solution
A wear-resistant coating is developed using a cobalt alloy containing chromium and silicon, with oxide particles dispersed in the coating, formed through laser overlaying with cobalt alloy powder passing through 150 or 425 mesh, ensuring oxide particles are 100 µm or less in size, enhancing wear resistance at temperatures up to 600°C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If TIG welding is used to form a wear resistant coating with cobalt alloy, then the coating can be formed on the sliding surface, but selective oxidization of chromium does not occur at temperatures below 600°C, resulting in poor wear resistance
Solution Approach 1:
The invention changes the chemical composition parameters of the cobalt alloy by adding specific amounts of aluminum (5-15 mass%) and silicon (2-10 mass%), which alters the oxidation behavior of the coating. These compositional changes enable oxide formation at lower temperatures, resolving the temperature-dependent wear resistance problem.
Solution Approach 2:
The invention creates a composite coating structure by combining cobalt alloy with aluminum and silicon elements. This composite material approach enables the formation of mixed oxides (Cr2O3, Al2O3, SiO2) that provide superior wear resistance across a broader temperature range, including temperatures below 600°C where conventional cobalt alloy coatings fail.
2Reliability
If chromium content is increased in the cobalt alloy to enhance selective oxidization, then wear resistance improves at high temperatures, but the cost and manufacturing complexity increase
Solution Approach 1:
Instead of relying solely on high chromium content, the invention creates a multi-element composite alloy system (Co-Cr-Al-Si) where aluminum and silicon work synergistically with chromium to form protective oxides. This composite approach achieves comparable or superior wear resistance with a more balanced and manufacturable alloy composition.
Solution Approach 2:
The invention optimizes the compositional parameters by specifying precise ranges for aluminum (5-15 mass%) and silicon (2-10 mass%), which modifies the oxidation kinetics and oxide formation temperature. This parameter optimization enables effective wear protection without requiring excessive chromium content, simplifying the alloy design and manufacturing process.
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 coating significantly improves wear resistance by forming chromium and silicon oxides even at temperatures below 600°C, reducing wear on sliding parts, as demonstrated by the fretting wear test results.
Implementation Method 1
a step of forming a wear resistant coating on a sliding surface of a sliding part by laser overlaying with an overlay material
Implementation Method 2
selective oxidization of chromium and the like contained in the cobalt alloy, is formed on the coating surface to enhance the wear resistance
Data Source
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Figure 5
AI summary
A sliding part (10) with a wear resistant coating includes a sliding part (12), and a wear resistant coating (14) provided on a sliding surface (12a) of the sliding part (12), and made of a cobalt alloy containing chromium and silicon. In the wear resistant coating, oxide particles (16) are dispersed which include an oxide containing chromium and silicon, and have a particle size of 100 µm or less when a cross section of the wear resistant coating (14) is observed using an optical microscope with a magnification of 100 times.