This research mainly focuses on the successful fabrication of nano-hydroxyapatite (nHA) reinforced WE43 alloy by two-pass friction stir processing (FSP). Microstructure evolution, mechanical properties, and in vitro corrosion behavior of FSPed WE43/nHA composite and FSPed WE43 alloy were studied. The results show that nHA particles are effectively dispersed in the processing zone, and the well-dispersed nHA particles can enhance the grain refine effect of FSP. The average grain sizes of FSPed WE43 alloy and WE43/nHA composite are 5.7 and 3.3 μm, respectively. However, a slight deterioration in tensile strength and yield strength is observed on the WE43/nHA composite, compared to the FSPed WE43 alloy, which is attributed to the locally agglomerated nHA particles and the poor quality of interfacial bonding between nHA particles and matrix. The electrochemical test and in vitro immersion test results reveal that the corrosion resistance of the WE43 alloy is greatly improved after FSP. With the addition of nHA particles, the corrosion resistance of the WE43/nHA composite shows an even greater improvement.

Micron Ti metal particles were incorporated into SiCp/7075Al composites using pressure infiltration. The interface structure between the Ti metal particles and the matrix during the casting processes were investigated. Results show that the dispersed unreacted Ti particles form mutual diffusion layer at the interface without the formation of low-temperature intermetallic phases during the solidification processes. The interaction between the micron Ti and the molten aluminum alloy is subject to the mutual diffusion coefficient of Ti–Al rather than the reaction activation energy. The tensile strength and plasticity of the composite were improved simultaneously due to the high interfacial bonding strength and released thermal misfit stress cause by the incorporated Ti metal particles.

The electric spindle is an essential component of modern CNC machine tools as it plays a crucial role in determining the performance and accuracy of the machine. However, the vibration of its bearing unit can significantly impact the spindle’s operational reliability and service life. Therefore, it is essential to develop a reliable method to distinguish between synchronous and asynchronous vibrations at both ends of the electric spindle. In this paper, we propose a signal similarity measurement method based on probability and l2-norm to address this issue. The proposed method employs EMD to decompose the vibration signals of the electric spindle bearings at both ends. Then, probability distribution and l2-norm are used to measure signal similarity effectively. This approach can effectively distinguish between synchronous and asynchronous vibrations at both ends of the electric spindle. Experimental testing was conducted to verify the effectiveness of this method. The results show that the proposed method is reliable and effective in distinguishing between synchronous and asynchronous vibrations at both ends of the electric spindle. This method has the potential to enhance the bearing’s service life and the operational reliability of the electric spindle.