研究大气等离子喷涂铸铁涂层微观结构随喷涂距离的形成规律及其对涂层在H₂SO₄、NaCl溶液中耐蚀性的影响。分别在不同喷涂距离条件下，采用大气等离子喷涂制备铸铁涂层，利用场发射扫描电子显微镜观察两种涂层的微观结构，利用图像法分析涂层孔隙率的变化，并分析涂层层间结合的变化。利用电化学极化法测定涂层在0.5 mol/L H₂SO₄溶液和3.5% NaCl溶液中的耐蚀性，分析两种涂层耐蚀性能的变化规律。两种涂层均呈现典型的层状结构特征。较70 mm喷涂距离制备的涂层C1，100 mm喷涂距离制备的涂层C2中含有较大、较多的孔隙和较多的粒子层间间隙，C1涂层和C2涂层的孔隙率分别为（1.53±0.48）%和（3.34±0.79）%。在两种溶液中两种涂层均发生钝化，C1涂层比C2涂层具有较正的腐蚀电位、较低的腐蚀电流密度和较高的极化电阻。在H₂SO₄溶液中，C1涂层的腐蚀电位、腐蚀电流密度和极化电阻分别为-0.448 V，5.727×10^-3 A·cm^-2，3153.6 Ω·cm²，而C2涂层分别为-0.458 V，6.537×10^-3 A·cm^-2，2663.6 Ω·cm²；在NaCl溶液中，C1涂层的腐蚀电位、腐蚀电流密度和极化电阻分别为-1.088 V，2.553×10^-4 A·cm^-2，3584.0 Ω·cm²，而C2涂层的分别为-1.098 V，6.159×10^-4 A·cm^-2，3341.9 Ω·cm²。较低的碰撞粒子-基体界面温度导致C2涂层较高的孔隙率，增加了其在腐蚀介质中产生电化学反应的原电池数量，最终导致其耐蚀性变差。

The formation law of atmospheric plasma sprayed cast iron coating microstructure with spraying distance and its corrosion resistance in H₂SO₄ and NaCl solution were studied. Cast iron coatings were prepared by atmospheric plasma spraying under different spraying distances. The microstructure of two coatings was observed by a field emission scanning electron microscope. The variation of coating porosity was examined by an image analysis method. The change of bonding between splats within the coatings was analyzed. The corrosion resistance of coatings was tested in 0.5mol/L H₂SO₄ and 3.5% NaCl solution by an electrochemical polarization method, and the variation laws for corrosion resistance performance of two coatings were analyzed. The results showed that both coatings exhibited a typical lamellar structure. Compared with the C1 coating prepared at 70 mm spraying distance, the C2 coating prepared at 100 mm spraying distance had more and larger pores and more nonbonded interlamellar interfaces. The porosity of C1 and C2 coatings was 1.53±0.48% and 3.34±0.79% respectively. Passivation appeared when the coatings were immersed in both solutions. Moreover, C1 coating showed a more positive corrosion potential, a lower corrosion current density, and a higher polarization resistance than C2 coating. In H₂SO₄ solution, the corrosion potential, corrosion current density and polarization resistance of C1 coating was -0.448 V, 5.727×10^-3 A·cm^-2 and 3153.6 Ω·cm² respectively, while those of C2 coating was-0.458 V,  6.537×10^-3 A·cm^-2 and 2663.6 Ω·cm²  respectively. In NaCl solution, the corrosion potential, corrosion current density and the polarization resistance of C1 coating was -1.088 V, 2.553×10^-4 A·cm^-2 and 3584.0 Ω·cm² respectively, while those of C2 was -1.098 V, 6.159×10^-4 A·cm^-2 and 3341.9 Ω·cm² respectively. The lower impact particle and interface temperature led to the higher porosity of C2 coating, hence the number of electrochemical reaction cells in the corrosive medium increased, therefore, the corrosion resistance of C2 coating became poor.