Comparison of Single and Multi-Layer Interface Strengths for Geosynthetic/Geosynthetic and Soil/Geosynthetic Interfaces

Low interface strength is a persistent problem in composite materials and cascades to limit a variety of bulk material properties such as lamina shear strength. Whiskerization has long been pursued as a method to reinforce the interphase and improve both the single fiber interface strength as well as the bulk properties. Recent developments have shown that ZnO nanowire whiskerization can effectively improve the properties of a bulk composite without requiring the high temperatures that previous deposition processes needed. Although the efficacy of a ZnO nanowire interphase has been established, the mechanism for adhesion of the interphase to the fiber has not been identified. Specifically, the addition of the ZnO nanowires to the surface of the fibers requires that the ZnO nanowires have strong chemical adhesion to the fiber surface. This work will create a variety of chemical environments on the surface of the fibers through new chemical functionalization procedures and quantify the surface chemistry through x-ray photoelectron spectroscopy. The effect of fiber surface chemistry on the adhesion of the ZnO is assessed through single fiber fragmentation testing. The interface strength is found to strongly correlate with the concentration of ketone groups on the surface of the fibers.

Aluminum–bronze coatings are successfully prepared on ductile iron by cold metal transfer (CMT) wire‐arc deposition. Interface characteristics and properties of aluminum–bronze coatings on ductile iron are investigated. The results demonstrate that heat input not only has a significant effect on the dilution rate, but also can affect the microstructure evolution and interface behavior. At low heat input, the dilution rate is close to zero, and incompletely dissolved graphite nodules and a few short cracks are distributed on the fusion line. The γ2 + α‐Cu eutectic phase is produced along the columnar grain boundaries of the deposited layer, and no Fe‐enriched phase is found. As heat input increases, the interface between aluminum bronze and cast iron changes from a diffusion joint to a metallurgical bond and from a single interface to a double interface. Fe‐enriched phases and Cu‐enriched phases are produced in the deposited layer and fusion zone, respectively. The microstructure of the fusion zone is mainly austenite, martensite, and ledeburite, resulting in the highest hardness near the interface. The interfacial bond strength of high heat input deposited layer is significantly higher than that of low heat input, and the latter has higher wear resistance than the former.