Mechanical part with a nanostructured tio2-cr2o3 ceramic coating and method for depositing a nanostructured tio2-cr2o3 ceramic coating on a substrate

Abstract

There is provided a method for depositing a TiO 2 -Cr 2 O 3 ceramic coating on a substrate. The method includes mixing a powder of sprayable nanostructured titanium(IV) oxide (n-TiO 2 ) and a powder of chromium(III) oxide (Cr 2 O 3 ), thereby obtaining a n-TiO 2 -Cr 2 O 3 powder blend. The method also includes thermal spraying particles of the n-TiO 2 -Cr 2 O 3 powder blend on the substrate at an in-flight particle temperature of or greater than 2350° C. and a particle in-flight velocity of or greater than 350 m/s, thereby obtaining a coated substrate.

1 . A method for depositing a ceramic coating on a substrate, the method comprising:
 mixing a powder of sprayable nanostructured titanium(IV) oxide (n-TiO 2 ) and a powder of chromium(III) oxide (Cr 2 O 3 ), thereby obtaining a n-TiO 2 -Cr 2 O 3  powder blend; and   thermal spraying particles of the n-TiO 2 -Cr 2 O 3  powder blend on the substrate at an average in-flight particle temperature of or greater than 2350° C. and an average particle in-flight velocity d or greater than 350 m/s, thereby obtaining a coated substrate.   
     
     
         2 . The method of  claim 1 , wherein the substrate is a metal substrate. 
     
     
         3 . The method of  claim 2 , wherein the metal substrate comprises one of titanium, a titanium alloy, stainless steel, steel, a high-performance nickel alloy, a high-performance cobalt alloy, bronze and a copper alloy. 
     
     
         4 . The method of  claim 1 , wherein the powder of sprayable n-TiO 2  comprises nanosized constituents agglomerated and/or sintered in microsized n-TiO 2  particles. 
     
     
         5 . The method of  claim 4 , wherein the nanosized constituents have a size ranging from 50 nm to 500 nm. 
     
     
         6 . The method of  claim 4 , wherein the microsized n-TiO 2  particles have a diameter distribution ranging from 4 μm to 100 μm. 
     
     
         7 . The method of  claim 1 , wherein the n-TiO 2 -Cr 2 O 3  powder blend comprises 40 wt % to 70 wt % of n-TiO 2  and 30 wt % to 60 wt % of Cr 2 O 3 . 
     
     
         8 . The method of  claim 7 , wherein the n-TiO 2 -Cr 2 O 3  blend comprises 53 wt % to 57 wt % of n-TiO 2  and 43 wt % to 47 wt % of Cr 2 O 3 . 
     
     
         9 . The method of  claim 1 , wherein the average in-flight particle temperature is 2400° C. to 2800° C. 
     
     
         10 . The method of  claim 1 , wherein the average in-flight particle temperature is 2500° C. to 2800° C. 
     
     
         11 . The method of  claim 1 , wherein the average particle in-flight velocity is greater than 400 m/s. 
     
     
         12 . The method of  claim 1 , wherein the average particle in-flight velocity is greater than 450 m/s. 
     
     
         13 . A mechanical part coated with a nanostructured titanium(IV) oxide-chromium(III) oxide (n-TiO 2 -Cr 2 O 3 ) coating, the coating having a microhardness of at least 1000 HV and a dry abrasion volume loss of less than 15 mm 3 . 
     
     
         14 . The mechanical part of  claim 13 , wherein the dry abrasion loss is less than 8.4 mm 3 . 
     
     
         15 . The mechanical part of  claim 13 , wherein the n-TiO 2 -Cr 2 O 3  coating comprises 40 wt % to 70 wt % of n-TiO 2  and 30 wt % to 60 wt % of Cr 2 O 3 . 
     
     
         16 . The mechanical part of  claim 13 , wherein the n-TiO 2 -Cr 2 O 3  coating comprises 53 wt % to 57 wt % of n-TiO 2  and 43 wt % to 47 wt % of Cr 2 O 3 . 
     
     
         17 . The mechanical part of  claim 13 , wherein the mechanical part is a ball-valve. 
     
     
         18 . A mechanical part coated with a ceramic coating, wherein the ceramic coating is deposited using the method of  claim 1 . 
     
     
         19 . A powder blend for use in thermal spraying for coating a substrate, the powder blend comprising 40 wt % to 70 wt % of sprayable n-TiO 2  and 30 wt % to 60 wt % of Cr 2 O 3 . 
     
     
         20 . The powder blend of  claim 19 , comprising 53 wt % to 57 wt % of n-TiO 2  and 43 wt % to 47 wt % of Cr 2 O 3 .