TY - JOUR 
A1 - Tomás Olmos, Pedro Antonio
T1 - Parametric study of the grit blasting technique as a susface activation method prior to coating processes by thermal spraying
Y1 - 2008
UR - http://hdl.handle.net/10317/94
AB - The aims of the study were to carry out a comparison of grit blasting and other surface pretreatment
processes and identify the relation between grit blasting parameters and coating
adhesion, because it can be assumed that the adhesion between substrate and coating
strongly depends on the physical properties of the substrate surface. By this way, in order to
improve the bonding between substrate and coating, it is necessary to study the influence of
different surface pre-treatment parameters and to compare different pre-treatment
techniques.
Grit blasting, water jet blasting and mechanicals processes (milling and grinding) have been
studied. In order to compare them, the roughness of the surface, the adhesive straights, the
topography, the contact surface and the residual stresses have been the considered
parameters to carry out the research. Two different substrates have been studied, AlMg7
and St_42.
For grit blasting, five different blasting parameters have been analyzed and combined to
obtain reliable results, attack angle, air pressure, lineal velocity, number of passes, and
distance between substrate and nozzle. After measuring the obtained values, the most
influence parameters were recombined and analyzed to obtain better surface conditions.
In the case of mechanicals processes (milling and grinding), the samples were studied for
different mechanical parameters, analyzed and compared with the other surface
pretreatments in order to obtain the most suitable method.
For water jet blasting, eight samples were sent to WLH (University of Hannover) to be
treated. To carry out the pretreatment, the velocity of the water jet blasting was modify while
the other blasting parameters remained constant, in order to compare the obtained values of
roughness, adhesion, activate area and residual stresses for water jet with grit blasting and
mechanical processes.
The next conclusions can be assumed:
The roughness is not so important than the topography to obtain the best adhesive bonding
between the substrate and the coating, and the best bonding was obtained for
homogeneous topographies (obtained for water jet blasting and grit blasting).
Comparing the surface pretreatments is observed that water jet blasting is the surface
pretreatment method which leads to the highest bonding between substrate and coating.
It can be assumed that a higher contact surface area leads to a better adhesion between
substrate and coating.
The residual stresses strongly depend on the surface pretreatment used. Grit blasting leads
to the highest compressive stresses while water jet blasting almost does not cause
variations and grinding obtains the same values than for a raw surface (untreated surface).
KW - Ingeniería de Sistemas y Automática
KW - Materiales cerámicos
LA - spa
ER -