Abstract
Keywords - Surface engineering, thermal spray, wear, on-line monitoring, on-line optimization.
Abstract - In this paper, the role of Thermal Spray in automotive industry is presented and also the need for a better quality control of these technologies. Thermal spay is said to be one of the most promising technologies to increase the performance of many engineering applications in chemical, textile, aerospace, power generation and automotive industries. The use of thermally sprayed parts in engines is being increased as new trends in automotive design are changing to more demanding engine performance and also to environmentally cleaner engines because coating higher properties in comparison to cast pieces. For these reasons, new materials and technologies should be applied in large series engine manufacturing. For example spraying cylinder bores, piston crowns, piston surface, valves, crankshafts, lambda sensors, synchronization rings can be coated with a broad range of materials.
To fulfill all the requirements, thermally sprayed parts properties should be designed very carefully. Lot of testing must be done in order to asses the feasibility of sprayed parts to replace some engine parts. However, all this research is pointless without controlling final process reliability because coating properties depend in a severe way on the process parameters for a given material/substrate combination.
For this reason, lots of new sensors for particle monitoring and thermal spray process control have appeared in the lasts years. With these sensors, in-flight particle properties such as velocity, temperature and sometimes even particle diameter are displayed in real time. A SprayWatch ® imaging system is used in the Thermal Spray Center and is based in a CCD fast camera without any light source, only the radiation emitted by the hot in-flying particles. Velocity, temperature and spatial and temporal distributions are available with this device. Relationships between process parameters and coating properties should be found in terms of particles velocity and temperature.
This relationships are found by joining two sets of information. On one hand, studying the properties of the spray coupons obtained by changing some given spraying parameters like in a classical thermal optimization process and on the other hand, measuring the in-flight particle properties with those spraying parameters.
The aim of this work is to find the suitable coating properties by means of an on-line optimization process. The establishment of an usage protocol for the monitoring device is done and thus, this kind of technology could be used in automotive industries that thermally spray some parts.