J. G. Legoux, J. Oberste Berghaus, Industrial Materials Institute / National Research Council Canada, Boucherville, QC, Canada; C. Moreau, National Research Council Canada (CNRC-NRC), Boucherville,, QC, Canada
The increasing use of HVOF coatings to replace hard chrome plating was initially motivated by the environmental and health risks associated with hexavalent chromium (Cr
6+) emissions during the plating process. Following performance optimization and proper coating selection, it has been found that the potential increase in performance and the cost/process-time reduction that the HVOF process enables often justifies its application. Recently, the use of Cr-containing alloys processed by HVOF has drawn attention to the potential release of Cr
6+ formed during heating of metallic Cr. For instance a new California regulation for airborne toxic control measure to reduce emissions of hexavalent chromium from thermal spraying is in preparation.
The present study focused on monitoring operator exposure during the HVOF spraying of WC-10%Co-4%Cr. The spraying was performed in a spray room in which 10 000 SCFM ventilation flow rate was imposed. The spraying was performed using a JP-5000 HVOF gun. Air sampling was performed using standard NIOSH 7300 and 7600 methods. Samples were also taken in the adjacent control room. As well, a portable sampler attached on the operator’s chest was used to monitor the operator exposure during a typical workday. Results indicate that even though metallic fumes or Co and Cr are present in the spray room during spraying, no Cr6+ was detected. It was concluded that an operator entering the spray room for a limited amount of time with the gun in operation would be exposed to only low fume levels that can be still reduced by wearing an appropriate respiratory mask.
The increasing use of HVOF coatings to replace hard chrome plating was initially motivated by the environmental and health risks associated with hexavalent chromium (Cr6+) emissions during the plating process. Following performance optimization and proper coating selection, it has been found that the potential increase in performance and the cost/process-time reduction that the HVOF process enables often justifies its application. Recently, the use of Cr-containing alloys processed by HVOF has drawn attention to the potential release of Cr6+ formed during heating of metallic Cr. For instance a new California regulation for airborne toxic control measure to reduce emissions of hexavalent chromium from thermal spraying is in preparation.
The present study focused on monitoring operator exposure during the HVOF spraying of WC-10%Co-4%Cr. The spraying was performed in a spray room in which 10 000 SCFM ventilation flow rate was imposed. The spraying was performed using a JP-5000 HVOF gun. Air sampling was performed using standard NIOSH 7300 and 7600 methods. Samples were also taken in the adjacent control room. As well, a portable sampler attached on the operator’s chest was used to monitor the operator exposure during a typical workday. Results indicate that even though metallic fumes or Co and Cr are present in the spray room during spraying, no Cr6+ was detected. It was concluded that an operator entering the spray room for a limited amount of time with the gun in operation would be exposed to only low fume levels that can be still reduced by wearing an appropriate respiratory mask.
