Multi-scale variographic analysis method for mixing quality evaluation of energetic materials based on Raman spectral imaging

The characterization of heterogeneity is crucial for defining the quality of energetic compounds and describing the evolution of uniformity during the mixing process of energetic materials. This study investigates the feasibility of tracking changes in mixing quality using a line-scan Raman hyperspectral imaging system combined with variance analysis. Initially, spectral unmixing techniques were applied to obtain a series of spatial distribution maps of pure components over time, allowing for a qualitative analysis of heterogeneity evolution during the mixing process. Based on the spatial state matrix and variogram analysis, a spatial heterogeneity distribution curve was proposed, and the spatial heterogeneity coefficient (S h ) was calculated to assess the mixing quality of energetic materials. Comparative results from simulated experiments demonstrate that the proposed S h value outperforms traditional evaluation metrics, such as Distribution Uniformity Index (DUI), Lacey Index (LI), Moran’s I (MI), Geary’s C (GC), the Entropy-based index (EI), in tracking variations in mixture homogeneity. Further validation through actual mixing experiments confirmed that the S h value effectively monitors the uniformity state of energetic components and provides critical evidence for diagnosing abnormal mixing behaviors. This coefficient innovatively integrates qualitative visualization with quantitative assessment, offering a comprehensive analytical tool for energetic material mixing processes. This work tackles the critical need for quantitative homogeneity assessment in energetic material mixing. We propose a novel methodology integrating line-scan Raman imaging, spectral unmixing, and variographic analysis.The approach constructs a spatial heterogeneity distribution curve and derives a quantitative coefficient (S h ). Validated by simulations and real mixing experiments, the S h index accurately tracks uniformity evolution, outperforming conventional indices and providing a robust tool for quality control. • A line scan Raman imaging system was used to monitor spatial heterogeneity during energetic material mixing. • The spatial heterogeneity coefficient (S h ) quantitatively tracks mixing uniformity by integrating spatial and concentration information. • Providing a method for endpoint estimation in energetic material mixing production.