Adaptive process control for achieving consistent particles' states in atmospheric plasma spray process

Abstract

The coatings produced by an atmospheric plasma spray process (APSP) must be of uniform quality. However, the complexity of the process and the random introduction of noise variables such as fluctuations in the powder injection rate and the arc voltage make it difficult to control the coating quality that has been shown to depend upon mean values of powder particles’ temperature and speed, collectively called mean particles’ states (MPSs), just before they impact the substrate. Here, we use a science-based methodology to develop a stable and adaptive controller for achieving consistent MPSs and thereby decrease the manufacturing cost. We first identify inputs into the APSP that significantly affect the MPSs and then formulate a relationship between these two quantities. When the MPSs deviate from their desired values, the adaptive controller is shown to successfully adjust the input parameters to correct them. The performance of the controller is tested via numerical experiments using the software, LAVA-P, that has been shown to well simulate the APSP.

Modified robust adaptive process control with improved transient performance and its application to atmospheric plasma spray process

“…The implementation of the MR-MRAC to the APSP is the same as that of Refs. [14] and [18] except the following form of the adaptive law is used:…”

“…We presented the complete details of the design of the adaptive process control for APSP (validation of numerical simulations, screening of process parameters, finding optimal input parameters, system identification, and the control design) are given in Refs. [13] and [14] for ceramic coating using ZrO 2 powder with a single torchsingle injector system and in Ref. [15] for FGCs using a mixture of the NiCrAlY and the ZrO 2 particles with a single torchtwo injector system.…”

Adaptive Control of the Atmospheric Plasma Spray Process for Functionally Graded Thermal Barrier Coatings

“…NiCrAlY and ZrO 2 Particles. Te three steps involved in addressing this issue are (i) using statistical analyses to identify signifcant input parameters, (ii) developing response functions relating signifcant input parameters to the MPSs, and (iii) numerically solving equations of the response functions to get starting values of input parameters [9] for producing an FGC.…”

“…Here, we use controllers based on a model reference adaptive control (MRAC) framework [9] whose robustness has been enhanced by incorporating in it the σ modifcation [10] and the low-frequency learning [11]. We called it the "modifed robust MRAC" (MR-MRAC) and illustrated its capability [12] in the presence of bounded external disturbances to adaptively adjust input parameters for a onematerial coating to achieve the desired MPSs within small tolerances.…”

Sealing Treatment of Plasma-Sprayed Cr3C2-NiCr/Al2O3-TiO2 Coating by Aluminum Phosphate Sealant Containing Al2O3 Nanoparticles

“…The plasma exits the gun tip, and the trajectory of the material from the tip to the steel substrate is determined by the temperature and velocity of the transport gas (Ref. 2 ). The APS is a conventional method for creating different types of coatings, especially ceramic-based ones.…”