Abrasive Blade Tip Coating Wear Resistance
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Solution Overview
Problem
Gas turbine engine blade tips experience rapid depletion of abrasive grit coatings during high radial interaction rates, leading to unwanted contact with Ti blade material and air seal abradable material, causing wear and potential sparking, which affects engine efficiency and safety.
Innovation Solution
A composite abrasive blade tip coating with SiC grit particles and a MCrAlY matrix, combined with smaller second grit particles and an adhesion layer, distributes cutting loads and reduces stress on the matrix, enhancing durability and wear resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If abrasive blade tip coating is used to maintain clearance, then cutting action is improved, but wear rate increases at high radial interaction rates
Solution Approach 1:
The patent applies composite materials by combining first grit particles (0.04-0.15mm) with second grit particles (0.01-0.1mm) within a MCrAlY matrix. This multi-scale composite structure allows the larger first grit particles to provide primary cutting action while the smaller second grit particles reinforce the matrix and distribute loads, preventing rapid depletion of the abrasive coating even at high radial interaction rates of approximately 40 inches per second.
2Shape
If abrasive coating is depleted, then clearance increases, but Ti blade material contact with seal causes sparking and wear
Solution Approach 1:
The patent implements preliminary action by creating a multi-layer protective structure before the Ti blade material contacts the seal. The abrasive coating with its dual grit particle system is applied in advance to maintain optimal clearance, preventing the underlying Ti blade material from exposing to and contacting the seal, thereby avoiding Ti sparking and associated harmful effects.
3Ease of manufacture
If single size grit particles are used, then manufacturing is simplified, but load distribution is insufficient reducing matrix stress
Solution Approach 1:
The patent applies local quality by using different grit particle sizes for different functional requirements within the same coating. The first grit particles (0.04-0.15mm) are optimized for cutting action, while the second grit particles (0.01-0.1mm) are specifically positioned to reinforce the matrix and distribute loads locally, preventing stress concentration and improving overall matrix strength.
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 maintains effective cutting action over multiple operating cycles, reduces wear on the matrix, and prevents Ti sparking by distributing loads between grit particles, ensuring optimal clearance and efficiency in gas turbine engines.
Implementation Method 1
a composite structure that distributes cutting loads from individual highly loaded grit particles to adjacent grit particles, thus reducing stress at the matrix which holds individual grit particles of the abrasive blade tip coating
Implementation Method 2
the blade tips will cut into the seal during those portions of the engine operating cycle when they come into contact with each other
Implementation Method 3
the blade tips will cut into the seal during those portions of the engine operating cycle when they come into contact with each other
Data Source
Figure 1
Figure 2
AI summary
An abrasive blade tip coating comprising a blade tip (14) having a top surface. A plurality of first grit particles (18) are dispersed over the top surface of the blade tip (14). A plurality of second grit particles (22) are closely packed between each of the plurality of first grit particles (18). The second grit particles (22) have a nominal size smaller than the first grit particles (18). A matrix material (20) is bonded to the top surface. The matrix material (20) envelops the second grit particles (22). The matrix material (20) is also bonded to and partially surrounds the first grit particles (18), the first grit particles (18) extending above the matrix material (20) and the second grit particles (22) relative to the top surface.