Method for coating compressor blade tips

Abstract

A method for forming a component having an abrasive portion includes forming the component and selectively forming a coating on the component using electric spark deposition to form the abrasive portion. A method for coating a blade tip with an abrasive material includes forming a blade having a tip and depositing a coating on the blade tip using electric spark deposition. A method includes providing a casing having an inner diameter surface, locating an abradable coating on a portion of the inner diameter surface, providing a blade configured to rotate within the casing and having a blade tip where the blade tip and the inner diameter surface of the casing form a seal, and depositing an abrasive coating on the blade tip using electric spark deposition so that the abrasive coating and abradable coating interact during rotation of the blade within the casing.

1 . A method for forming a component having an abrasive portion, the method comprising:
 forming the component; and   selectively forming a coating on the component using electric spark deposition to form the abrasive portion.   
     
     
         2 . The method of  claim 1 , wherein the component is a blade, and wherein the abrasive portion is located at a blade tip. 
     
     
         3 . The method of  claim 1 , wherein the coating has a surface roughness (R a ) between about 1.25 micrometers (50 microinches) and about 5 micrometers (200 microinches). 
     
     
         4 . The method of  claim 1 , wherein the coating has a thickness between about 0.025 millimeters (0.001 inches) and about 0.51 millimeters (0.020 inches). 
     
     
         5 . The method of  claim 4 , wherein the coating has a thickness between about 0.10 millimeters (0.004 inches) and about 0.305 millimeters (0.012 inches). 
     
     
         6 . The method of  claim 1 , wherein the coating is selected from the group consisting of alumina, zirconia, chromia, hafnia, ceria, titania, silica and combinations thereof. 
     
     
         7 . The method of  claim 1 , wherein the coating is selected from the group consisting of silicon carbide, tungsten carbide, titanium carbide, boron carbide, cubic boron nitride, aluminum diboride, diamond and combinations thereof. 
     
     
         8 . The method of  claim 1 , wherein a metal oxide content of the coating is between about 25% by weight and about 100% by weight. 
     
     
         9 . The method of  claim 1 , wherein the step of selectively forming the coating on the component using electric spark deposition, comprises:
 applying a voltage between an electrode containing aluminum, zirconium, chromium, hafnium, cerium, titanium, silicon and combinations thereof and the component; and   moving the electrode toward the component so that a portion of the electrode is deposited on the component.   
     
     
         10 . The method of  claim 1 , wherein the coating is formed to provide an abrasive:abradable wear ratio of the abrasive portion of the component to an abradable portion of a stationary component adjacent the component, and wherein the abrasive:abradable wear ratio is between about 1:50 and about 1:500. 
     
     
         11 . The method of  claim 10 , wherein the abrasive:abradable wear ratio is about 1:400. 
     
     
         12 . The method of  claim 10 , wherein the abradable portion of a stationary component comprises a CoNiCrAlY or NiCoCrAlY alloy. 
     
     
         13 . The method of  claim 1 , wherein the coating is formed without use of masking techniques. 
     
     
         14 . A method for coating a blade tip with an abrasive material, the method comprising:
 forming a blade having a tip; and   depositing a coating on the blade tip using electric spark deposition.   
     
     
         15 . The method of  claim 14 , wherein the coating is formed without use of masking techniques. 
     
     
         16 . The method of  claim 14 , wherein the coating comprises alumina, zirconia, chromia, hafnia, ceria, titania, silica and combinations thereof. 
     
     
         17 . A method comprising:
 providing a casing having an inner diameter surface;   locating an abradable coating on a portion of the inner diameter surface;   providing a blade configured to rotate within the casing and having a blade tip, wherein the blade tip and the inner diameter surface of the casing form a seal; and   depositing an abrasive coating on the blade tip using electric spark deposition so that the abrasive coating and abradable coating interact during rotation of the blade within the casing.   
     
     
         18 . The method of  claim 17 , wherein the abradable coating comprises a CoNiCrAlY or NiCoCrAlY alloy. 
     
     
         19 . The method of  claim 17 , wherein the abrasive coating has a thickness between about 0.025 millimeters (0.001 inches) and about 0.51 millimeters (0.020 inches). 
     
     
         20 . The method of  claim 17 , wherein the abrasive coating comprises alumina, zirconia, chromia, hafnia, ceria, titania, silica and combinations thereof.