Substrates Coated with Wear Resistant Layers and Methods of Applying Wear Resistant Layers to Same

Abstract

Components with improved erosion resistance are disclosed. A surface of the component or a substrate of the component is modified by coating the substrate with an elastomer layer. The elastomer layer is then modified by embedding hard particles onto an outer side of the elastomer layer. The hard particles exhibit higher fractured toughness providing enhanced erosion protection. The elastic properties of the elastomer experience little reduction because the surface embedded particles are located only at the outer side or outer surface of the elastomer layer. Therefore, the bond between the inner side of the elastomer layer and the substrate or component surface is not interfered with and the potential for electro-chemical corrosion and poor adhesion are not increased by the presence of the hard particles as the hard particles are located away from the inner face between the elastomer layer and the substrate.

Description

TECHNICAL FIELD[0001]This disclosure relates generally to erosion resistant coatings for substrates and methods of applying such erosion resistant coatings to substrates.BACKGROUND[0002]The durability of helicopter rotor blades is dependent to a large extent on the erosion of the component by friction or by impact of finely divided solid or liquid particles. There is no way to avoid this friction or particulate impact during use of these components and therefore some means is needed to protect the components against erosion.[0003]For example, the air through which the helicopter rotor blade rotates may contain particulate matter, such as sand. The size of the sand particles typically ranges from about 0.1 to 2000 microns and more typically from about 20 to 30 microns in diameter. If the air contains sand, the sand impinges upon the rotor blades as they rotate, thereby causing abrasion to the blades, or at least to portions thereof. Unless the blades are adequately protected, such re...

AI Technical Summary

Benefits of technology

This patent describes a method to make a substrate more resistant to erosion by coating it with an elastomer layer. The elastomer layer is partially cured and then particles are added to the layer to control its surface energy. This helps to make the substrate more durable and resistant to erosion.

Problems solved by technology

There is no way to avoid this friction or particulate impact during use of these components and therefore some means is needed to protect the components against erosion.

If the air contains sand, the sand impinges upon the rotor blades as they rotate, thereby causing abrasion to the blades, or at least to portions thereof.

Unless the blades are adequately protected, such repetitive abrasive contact can eventually cause the blades to erode.

The potential for erosion also exists if the rotor blades circulate through air containing water droplets.

Although the size of the water droplets is typically greater than the size of sand, under high velocity conditions, water droplets may behave similar to sand, thereby causing erosion to the rotating rotor blades.

Moreover, the combination of rain and sand can exacerbate the amount of abrasion and / or erosion.

As a result, when translating a component through air comprising both rain and sand, the potential for erosion further increases.

Specifically, as the impact force increases, so does the potential for erosion.

Therefore, the leading edge is the portion of the blade most susceptible to erosion caused by the abrasive contact of particulate matter.

In other words, the potential for erosion increases as the speed of the blade increases.

Therefore, the potential for erosion is greatest at the outboard tip of the leading edge of the rotor blade.

The extended exposure of the nickel to the impinging particulate matter, however, causes the ductile metal leading edge to erode.

Because the ductile metal leading edge is adhesively bonded to the blade, replacing the ductile metal leading edge requires a certain amount of time and skill, which is not typically available in the field.

Depot repairs are undesirable because depot repairs increase the amount of time that the aircraft is unavailable in comparison to a field level repair.

Because the replacement of the ductile metal leading edge is considered a depot repair, bonding ductile metal onto the leading edge of a rotor blade is an undesirable technique for minimizing erosion.

Unfortunately, the elastomeric tape must be replaced more frequently than a nickel leading edge and the ability of the elastomer to resist erosion caused by the combined rain and sand is less than that of nickel.

Specifically, the elastomeric tape fails to adequately absorb the impact energy of the particulate matter.

Without adequate absorption capabilities, the elastomer fails to dissipate the impact energy, thereby allowing the particulate matter to erode the elastomer.

Unfortunately, the particles at the interface of the elastomer layer and the substrate can cause poor bonding to the substrate and / or electrochemical corrosion problems such as a galvanic coupling.

Further, the embedded particles can adversely affect the elastic properties of the elastomer coating thereby reducing the ability of the elastomer coating to absorb energy from particles in the air, such as sand, water droplets and other debris.

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