結果顯示，電流、氬氣流量與氫氣流量皆會影響 Ni-Cr-6Al 塗層硬度，且三項因子之 P 值皆小於 0.05，表示對硬度具有顯著影響。其中，氬氣流量為主要影響因子，貢獻度為 44.86%，高於電流之 16.57% 與氫氣流量之 17.43%。在本研究條件下，最佳參數為電流 600 A、氬氣流量 40 SLPM、氫氣流量 15 SLPM，其平均硬度為 94.26 HRD，並具有最高訊噪比，最大拉伸強度為 51.70 MPa，於測試組別中排名第二，顯示該參數不僅硬度表現最佳，也兼具良好附著強度與穩定性。金相觀察亦顯示，此條件下塗層層狀結構較均勻且緻密，孔隙較少，且界面完整性良好。綜合硬度、訊噪比、微結構、孔隙率與最大拉伸強度結果，本研究所建立之最佳參數可作為 Ni-Cr-6Al 合金粉末應用於航太維修大氣電漿噴塗製程之品質管控與參數設定參考。;This study aims to use aerospace Ni-Cr-6Al alloy powder as the coating material to fabricate metallic coatings by atmospheric plasma spraying. The effects of process parameters on coating hardness， microstructure， porosity and tensile strength were investigated. Ni-Cr-6Al alloy powder provides good high-temperature oxidation resistance， corrosion resistance， and adhesion， making it suitable for surface protection and repair of high-temperature aerospace engine parts. Since particle melting， in-flight velocity， and impact deposition behavior affect coating quality during plasma spraying， finding optimized process parameters is important for practical applications.
A three-factor， three-level full factorial design was adopted. The selected factors were current， argon flow rate， and hydrogen flow rate. The current levels were 300， 450， and 600 A; the argon flow rates were 40， 60， and 80 SLPM; and the hydrogen flow rates were 5， 10， and 15 SLPM， making 27 experiments totally. After spraying， Rockwell hardness testing， metallographic observation， porosity analysis， microstructural and elemental analysis， and tensile testing were performed. Signal-to-noise ratio analysis and ANOVA were used to evaluate the effects of each parameter on coating performance.
The results showed that current， argon flow rate， and hydrogen flow rate all significantly affected the hardness of the Ni-Cr-6Al coating， with P-values lower than 0.05. Among them， argon flow rate was the most influential factor， with a contribution of 44.86%， higher than hydrogen flow rate at 17.43% and current at 16.57%. Finally， the optimal parameter combination was 600-A current， 40-SLPM argon flow rate， and 15-SLPM hydrogen flow rate. This condition achieved an average hardness of 94.26 HRD， the highest signal-to-noise ratio， and a maximum tensile strength of 51.70 MPa， ranking second among the tested groups. Metallographic observation， porosity analysis， and elemental analysis results also showed that this coating had a good structure and interfacial integrity. Overall， the optimized parameters completed in this study can provide as a reference for quality control and parameter setting in atmospheric plasma spraying of Ni-Cr-6Al alloy powder for aerospace repair applications.
