## 4 Discussion of the Research Results  
Analysis of the Influence of the Main Parameters of Microplasma Arc and the Two-Phase Flow of \"Microplasma-Filler Powder\" on the Dimensions of the Deposited Layer  
During the manufacturing of spatial products via additive building-up of the layers using successive deposition, the size of the built-up layer (deposited metal bead) is a very important parameter, as it determines the characteristics of the shape and surface, as well as the accuracy of the product. In this regard, it is necessary to solve the problem of determining an optimal ratio of the coefficients of concentration of the specific flows of filler powder and microplasma arc heat, as well as the ratio of the effective diameters of the powder feeding spot and heating spot. Another important task is reducing the powder losses during the additive building-up of the part. The main cause of powder filler losses is the movement of the dispersed particles over the periphery of the plasma arc column and, moreover, their elastic reflection from the deposited product surface beyond the zone of the formed deposited metal pool [35]. Therefore, in the case of the realization of additive technology of building up thin-walled metal products with a wall thickness of approximately 3.5 mm, it is important to control the dimensions and characteristics, in particular, the concentration of the microplasma arc during the addition of the powder filler. In particular, to optimize the trajectories of filler material movement in the plasma arc, it is recommended to add filler \begin{table}
\begin{tabular}{c c c c c} \hline \hline \(\mathbf{D_{\text{T}}}\). **mm** & **I. A** & **B. mm** & \(\mathbf{M_{\text{D}}}\). **g/min** & **PUC** \\ \hline \multirow{4}{*}{4.5} & 25 & 2.5 & 4.7 & 0.72 \\ \cline{2-5}  & 30 & 4.0 & 4.5 & 0.69 \\ \cline{2-5}  & 35 & 5.0 & 4.6 & 0.70 \\ \hline \multirow{4}{*}{3.5} & 25 & 2.5 & 5.3 & 0.82 \\ \cline{2-5}  & 30 & 3.5 & 5.2 & 0.80 \\ \cline{2-5}  & 35 & 4.5 & 5.4 & 0.83 \\ \hline \multirow{4}{*}{2.5} & 25 & 2.5 & 5.6 & 0.86 \\ \cline{2-5}  & 30 & 3.0 & 5.7 & 0.88 \\ \cline{1-1} \cline{2-5}  & 35 & 3.5 & 5.8 & 0.89 \\ \hline \hline \end{tabular}
\end{table} 
Table 9: The deposited metal’s specific weight \(M_{\text{d}}\) and bead width \(B\) during additive microplasma deposition depending on the diameter of the plasmatron transporting nozzle channel, \(d_{\text{T}}\). powders to the arc at the velocity of not less than 2 m/s at up to 40-45\({}^{\circ}\) angle with the plasmatron axis [36]. To determine the best conditions for focusing the two-phase flows of microplasma, filler powder, which ensures filler material transportation through the high-temperature region of the microplasma arc to the deposition pool at the formation of the deposited layer of approximately 3.5 mm width, lets us analyze the studied technological features of additive microplasma deposition (Table 9). The weld pool shape becoming close to a circle at typical modes of microplasma powder deposition allows us to assume the correspondence to the normal law of radial distribution of the filler material in the microplasma arc on the level of the surface of the anode (the weld pool). In order to check the assumption, the effective diameter \(d_{\text{ef}}\) of the powder feeding spot was determined (Table 10), the comparison of which with the concentration of the specific heat flow on the product surface, \(2r_{0}\), allows the tentative determination of PUC. It was found that a reduction in the diameter of the microplasmatron-transporting nozzle channel from 4.5 m to 2.5 mm ensures a change in area \(S_{\text{ef}}\) of the effective spot of powder feeding from 38.5 mm to 12.6 mm\({}^{2}\), i.e., approximately three-fold. An analysis of the experimental data (Table 10) shows that an increase in PUC value in the range from 0.72 to 0.88 corresponds to a reduction in the equivalent radius \(r_{0}\) of the powder feeding spot.