Oxidation-Resistant Nickel Braze Putty for Large Casting Voids
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Solution Overview
Problem
Existing methods for repairing complex cast parts with defects, such as residual casting core material, dross, inclusions, and porosity, are limited by the inability to effectively fill large voids and provide sufficient environmental resistance, especially when welding is unsuccessful due to the alloy used.
Innovation Solution
A braze putty composition comprising a sacrificial binder with a low glass transition temperature and a blend of high and low melting temperature nickel alloys, which is applied to the repair area, allowing for the removal of the sacrificial binder and fusion of the nickel alloys to create a defect-free, environmentally resistant repair.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If welding is used to repair large defects in cast parts, then the repair strength can be improved, but the process becomes unsuccessful when the alloy used is incompatible with welding
Solution Approach 1:
The invention changes the fundamental parameters of the repair approach by transitioning from welding (high-temperature fusion process) to brazing (lower-temperature diffusion process). The braze putty composition uses nickel-based alloys with controlled melting ranges that are applied in a soft state and then heated to fuse without requiring the high temperatures and conditions needed for welding incompatible alloys, thereby achieving reliable repairs where welding fails.
Solution Approach 2:
The invention employs a composite braze putty material consisting of nickel-based alloy powders (including specific compositions with elements like chromium, aluminum, cobalt, and boron) combined with a sacrificial binder. This composite structure allows the material to be applied in a workable state and then transformed into a strong, defect-free repair that is compatible with the base alloy, overcoming the limitations of welding on certain alloys.
2Ease of manufacture
If mechanical means are used to remove defects, then the part can be repaired, but large voids cannot be effectively filled
Solution Approach 1:
The braze putty acts as an intermediary material that fills the voids created by mechanical defect removal. The putty is applied in a soft, moldable state that allows it to conform to and fill irregular void spaces, then it is heated to fuse and create a defect-free repair. This intermediary approach overcomes the limitation of mechanical means alone, which cannot effectively fill large or irregular voids.
Solution Approach 2:
The invention utilizes parameter changes in the braze putty material, which transitions from a soft, moldable state at room temperature to a fused, solid state after heating. This phase and property change allows the material to be easily applied to fill voids of various sizes and shapes, then transformed into a strong, precise repair that meets manufacturing requirements.
3Ease of operation
If conventional braze materials are used, then the repair process is simple, but environmental resistance is insufficient
Solution Approach 1:
The invention employs a composite braze putty material with specific nickel-based alloy compositions containing elements like chromium (for oxidation resistance), aluminum (for environmental resistance), and controlled boron content. This composite structure maintains ease of application while providing superior environmental resistance that conventional braze materials cannot achieve, particularly in high-temperature or corrosive environments.
Solution Approach 2:
The invention applies local quality by incorporating specific alloying elements in controlled amounts within the braze putty composition. The nickel-based alloy includes chromium and aluminum for oxidation and environmental resistance, with boron controlled at specific levels to prevent excessive grain growth while maintaining flow characteristics. This localized compositional control provides enhanced environmental resistance where needed without compromising the overall ease of operation.
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 braze putty composition effectively fills large voids and provides environmental resistance equivalent to a cast part without defects, enabling the repair of complex cast parts with improved durability and reliability.
Implementation Method 1
the sacrificial binder comprises an acrylic polymer having a glass transition temperature below about 20° C.
Implementation Method 2
a blend of high and low melting temperature nickel alloys, which is applied to the repair area, allowing for the removal of the sacrificial binder and fusion of the nickel alloys
Data Source
AI summary
Disclosed is a braze putty composition including a sacrificial binder, a first nickel alloy and a second nickel alloy, a method of making the putty, and a method for using this putty to repair castings.