Mechanism Of Influence Of Powder Concentration And Temperature Distribution On The Morphology Of The Cladding Layer

Laser cladding can be used as a laser as a heat source,heating a special ratio of metal powder on the surface of parts to form an ideal performance of reinforced coating technology.The microstructure of laser cladding metal is dense and uniform.Due to the rapid cooling of the laser cladding layer,the segregation of elements can be reduced during the process of laser cladding,and the ability of the coated tissue to resist electrochemical corrosion can be improved,which makes this technology play an important role in metal surface strengthening,valuable parts repair and manufacturing.Aiming at the precise cladding control of laser cladding corrosion resistant coatings,this paper studies the influence of powder particle concentration and temperature distribution on the laser cladding substrate on the cladding morphology.Combined with the geometric parameters of the cladding layer topography,a prediction model of the cladding layer topography is established,and the cladding layer topography is predicted and verified by experiments.The main studies were as follows.Firstly,the distribution of powder concentration was studied.The distribution of powder concentration on the surface of the substrate was studied by changing the flow rate of the carrier gas.The results showed that with the increase of the flow rate of the carrier gas,the maximum powder concentration on the surface of the substrate changed,showing a situation of first increasing and then decreasing.The sink point of the powder under the nozzle is constantly approaching the surface of the matrix from the bottom of the matrix,and finally moves to the position above the surface of the matrix.The powder concentration distribution equation on the surface of the matrix was fitted,and the relationship between the A value in the powder concentration equation and the corresponding powder carrying gas flow rate was established,and the powder concentration distribution on the matrix was verified.Secondly,the distribution of powder temperature was studied.The results show that when the powder gas flow rate is small,the powder concentration on the surface of the matrix is small,resulting in a small powder particle temperature.With the increase of the powder gas flow rate,the powder concentration on the surface of the matrix increases,the heat transfer becomes stronger,and the powder particle temperature increases continuously.The powder temperature distribution equation on the surface of the matrix was fitted,and the relationship between the A value in the powder temperature equation and the corresponding powder carrying gas flow was established,and the powder temperature distribution on the matrix was verified.Finally,based on the geometric parameters(width and height)of the cladding topography obtained from the experiment,the distribution equations of geometric parameters and powder particle concentration and temperature were established,the governing equations of geometric parameters(width and height)were obtained,and the cladding topography was predicted.The results showed that the influence of powder temperature distribution was positively correlated with the height of the cladding layer,and negatively correlated with the width of the cladding layer.The distribution of powder concentration was negatively correlated with both cladding width and height.The error rate between the predicted width and height of the cladding layer and the test value was less than 6%,and the minimum error rate was 2.40%.The prediction model had strong accuracy.This work realizes the prediction control of the topography of the cladding layer by taking the flowrate of the carrying powder gas as a variable,which provides a new thinking direction for the prediction of the topography of the cladding layer.