The variation of surface residual stress with spray frequency in detonation-sprayed coatings is not universally predictable, as it can depend on several factors such as the material being sprayed, the spraying process parameters, and the specific coating application. However, there are some general trends that have been observed in certain cases. It's important to note that the information I provide is based on general trends, and specific experimental data or studies may be required for a more accurate understanding of the behavior in a particular system.
Decreasing trend: In some cases, an overall decreasing trend of surface residual stress with increasing spray frequency has been observed. This can be attributed to higher spray frequencies leading to increased particle velocities and kinetic energy. The higher kinetic energy can result in more intense plastic deformation and thermal effects during impact, which can lead to reduced residual stresses.
Optimum frequency: In certain cases, an optimum spray frequency may exist where the surface residual stress is minimized. This optimum frequency is typically associated with a balance between the impact energy and cooling rate. At this frequency, the coating experiences sufficient energy for bonding and consolidation without excessive thermal effects that can induce high residual stresses.
Oscillatory behavior: Some studies have reported oscillatory behavior in surface residual stress as spray frequency is varied. This behavior can arise due to complex interactions between particle impact, bonding, and heat transfer processes. The oscillations in residual stress can be attributed to variations in the coating microstructure and the resulting stress distribution.
It is important to note that the relationship between spray frequency and surface residual stress in detonation-sprayed coatings can be influenced by various other parameters, such as powder characteristics, particle velocity, substrate material, and coating thickness. These factors can interact in a complex manner, and the specific behavior may vary from system to system.
To obtain a more accurate understanding of the relationship between spray frequency and surface residual stress in a specific coating application, it is recommended to consult relevant experimental studies or research literature that specifically investigates the material and process parameters of interest. Conducting experiments or numerical simulations tailored to the specific system can also provide valuable insights.