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A total of 55% SiCp/ZL102 composites were surface metalized by electroless nickel plating. The Al-17Cu-8 Mg-2Ni as-cast brazing alloy was prepared into foil-like by melt spinning machine through ultra-cold thin strip system. The obtained foil-like brazing alloy has better flexibility, more uniform element distribution, and higher free energy than the as-cast brazing alloy. The 55% SiCp/ZL102 composites after nickel plating were brazed by different brazing processes in the air. The Ni–P coating effectively inhibited the formation of alumina film on the composite surface. However, the presence of an oxide layer on the foil filler caused a negative effect on the Ni–P coating and hindered the diffusion between elements. SiC, Ni2Al3, and other phases were detected in the joint port. The characteristic morphologies such as furrows and massive particles indicated that the fracture behavior is brittle fracture. The maximum shear strength of the joint was 88.31 MPa at 590 °C.

High-volume-fraction aluminum matrix composites reinforced with SiC particles (SiCp/Al MMCs) have been widely used in aerospace and other fields due to their excellent properties. However, joining high-volume-fraction SiCp/Al MMCs is challenging. In this work, an efficient and high-strength method was developed to join high-volume fraction SiCp/Al MMCs. SiCp/ZL102 composites (55 vol.%) were brazed by Al-17.0Cu-8.0 Mg-1.5Ni filler metal in atmospheric environment. Compared to as-cast filler metal, the foil-like filler metal prepared by melt-spinning has finer grains and superior diffusion performance. The microstructure, shear strength, and fracture morphology of the joint were investigated. The brazed joint at 580 °C for 30 min exhibited a maximum shear strength of 92 ± 2 MPa, and the foil-like filler metal had optimal bonding performance with the base material. Meanwhile, the elements between the filler metal and base material interdiffused and metallurgical reacted. As a result, the oxide films on the surface of filler metal and of SiCp/ZL102 composites were broken; furthermore, Al2MgO4and MgO were formed in the joint interface based on the redox reaction. The fracture type of brazed joint was a mixed ductile–brittle fracture.

BackgroundThe prevalence of osteoarthritis of the atlanto-odontoid joint has been reported by radiology, autopsy, and conventional computed tomography (CT), but the prevalence has not yet been assessed by multidetector computed tomography (MDCT).PurposeTo reveal the prevalence of osteoarthritis of the atlanto-odontoid joint and to analyze the inter-relationships among gender, age, and osteoarthritis with MDCT in adults.Material and MethodsFirst, a series of 700 selected domestic patients aged >18 years undergoing an upper cervical MDCT scan were divided equally into seven age groups. Second, using the postprocessing technique of multiplanar reconstruction, osteoarthritis of the atlanto-odontoid joint was viewed from any direction and classified into four grades, which were normal, mild, moderate, and severe. Lastly, the incidence of the different grades of osteoarthritis was assessed, and the reproducibility was tested.ResultsThere was no significant difference between gender and osteoarthritis of atlanto-odontoid joint (P > 0.05). The rate of osteoarthritis was 16% in the age group 18–25 years, 23% in the age group 25–30 years, 33% in the age group 30–40 years, 54% in the age group 40–50 years, 70% in the age group 50–60 years, 87% in the age group 60–70 years, and 93% in the age group >70 years. Mild osteoarthritis appeared at the earliest at age 19.6 years, moderate osteoarthritis in at earliest at age 24.2 years, and severe osteoarthritis at the earliest at age 48.5 years. The inter-observer reliability was excellent (k = 0.86).ConclusionOsteoarthritis of the atlanto-odontoid joint could be detected by MDCT in a young adult. It increased rapidly with increasing age on MDCT.