Method and equipment for removal of ceramic coatings by co2 coatings

Abstract

A method for removing ceramic coatings using a special equipment without modifying the characteristics of the substrate such as roughness and thickness and able to prepare the substrate to be recoated with a new ceramic layer, is provided. The removing of the ceramic coating without damaging the substrate characteristics is obtained by a combination of coating/substrate pre-heating by irradiation during or immediately before the stripping and improved solid CO 2 blasting equipment and parameters.

1 . A method for removing ceramic coatings ( 2 ) applied on metallic, ceramic, plastic or composite substrates ( 1 ), comprising stripping by blasting phase with solid CO2 ( 4 ) blasting; said method being applied without modifying or damaging the substrate ( 1 ) characteristics, thickness and roughness, and being able to prepare the substrate ( 1 ) to be recoated with a new ceramic layer ( 2 ); characterized in that provides a combination of coating( 2 )/substrate( 1 ) pre-heating by irradiation during or immediately before said stripping by blasting with solid CO2 ( 4 ). 
     
     
         2 . Method, as recited in  claim 1 , wherein said components are pre-heated in sequence in the pre-heating stations ( 5 ) then the coating is stripped with solid CO2 ( 4 ) up to the quenching of the process, namely room temperature; the steps of pre-heating and solid CO2 blasting are repeated for each substrate up to the complete coating removal. 
     
     
         3 . Method, as recited in  claim 1 , characterized in that apply a continuous, namely not pulsed, solid CO2 blasting flow. 
     
     
         4 . Method, as recited in  claim 3 , characterized in that said solid CO2 blasting flow is applied with constant pressure. 
     
     
         5 . Method, as recited in  claim 1 , characterized in that said coating/substrate pre-heating by irradiation applies with a speed in a range of 1° C./min to 100° C./min. 
     
     
         6 . Method, as recited in  claim 1 , characterized in that said coating/substrate pre-heating by irradiation is increased up to 1000° C. 
     
     
         7 . Method, as recited in  claim 3 , characterized in that said continuous flow applies a mass flow of solid CO2 in a range of about 100-3500 g/min. 
     
     
         8 . Method, as recited in  claim 3 , characterized in that said continuous flow can vary the pressure in a range of 1-30 bar. 
     
     
         9 . Method, as recited in  claim 1 , characterized in that is able to jet the solid CO 2  saving the pellets density in a range of 1.525-1.6 g/cm 3  before the impact on the ceramic coating. 
     
     
         10 . Method, as recited in  claim 1 , characterized in that removes ceramic coating with a speed of 1-100 cm/min. 
     
     
         11 . Equipment for removing ceramic coatings ( 2 ) applied on metallic, ceramic, plastic or composite substrates ( 1 ), comprising stripping by blasting phase with solid CO2 ( 4 ) blasting; characterized in that comprises at least a pre-heating Station ( 5 )and at least sand Blasting Machine Station ( 20 ) for blasting the ceramic coatings ( 2 ) with solid CO 2  and comprising at least a compressor and at least a feeder unit in order to feed dry ice into one or more spray guns ( 19 ), obtaining a solid CO 2  blasting flow by the combination of the application in the blasting device of feeder and spray gun ( 3 ) two-hose nozzle. 
     
     
         12 . Equipment, as recited in  claim 11  characterized in that is made by N pre-heating stations ( 5 ) and M sand blasting machine stations ( 20 ), where N=1-100 and M=1-50. 
     
     
         13 . Equipment, as recited in  claim 11  characterized in that dry ice pellets ( 4 ) are continuously dispensed in the feedstock area ( 12 ) of the feeder unit and an air pressure flow, in a range of 1-5 bar, moves the accumulated pellets up to two-hose nozzle of spray guns ( 3 ); solid CO 2  pellets are fed in the main nozzle hose by axial injection, and a second pipe with high pressure air up to 30 bar is connected with the convergent/divergent nozzle so that the high pressure air is accelerated by convergent/divergent nozzle up to supersonic speed; the dry ice pellets are injected directly in the accelerated high pressure air stream after the nozzle throat ( 19 ). 
     
     
         14 . Equipment, as recited in  claim 11  characterized in that said pre-heating station comprises infrared (IR) lamps ( 6 ) in a range of wavelength of 1-10 μm and power output in a range of 1000-50000 W. 
     
     
         15 . Method, as recited in  claim 1 , characterized in that does not include the step of pre-damaging the ceramic coating before stripping step by dry ice blasting.