Bionic Stepping Motors Driven by Piezoelectric Materials

By imitating the behavioral characteristics of some typical animals, researchers develop bionic stepping motors to extend the working range of piezoelectric materials and utilize their high accuracy advantage as well. A comprehensive review of the bionic stepping motors driven by piezoelectric materials is presented in this work. The main parts of stepping piezoelectric motors, including the feeding module, clamping module, and other critical components, are introduced elaborately. We classify the bionic stepping piezoelectric motors into inchworm motors, seal motors, and inertia motors depending on their main structure modules, and present the mutual transformation relationships among the three types. In terms of the relative position relationships among the main structure modules, each of the inchworm motors, seal motors, and inertia motors can further be divided into walker type, pusher type, and hybrid type. The configurations and working principles of all bionic stepping piezoelectric motors are reported, followed by a discussion of the advantages and disadvantages of the performance for each type. This work provides theoretical support and thoughtful insights for the understanding, analysis, design, and application of the bionic stepping piezoelectric motors.

Control of the hydrophobicity of rare earth oxide coatings deposited by solution precursor plasma spray by hydrocarbon adsorption

The basis of the hydrophobicity of lanthanide rare earth oxides(REOs)has been the subject of considerable debate.To explore this question,the wetting behaviors and surface compositions of hierarchicallystructured Yb_(2)o_(3)(one of the REOs)coatings and non-REO Al_(2)o_(3)coatings deposited via solution precursor plasma spray process were investigated in this work.The Yb_(2)o_(3)coatings were subjected to a number of post-deposition treatments including vacuum(1-15 Pa)treatment,Ar-plasma treatment,heat treatment(400℃),long-time air exposure and ultra-high vacuum(1×10^(-7)Pa)treatment.Subsequent characterization showed that different post-deposition treatments resulted in different wetting behavior for the Yb_(2)o_(3)coatings which correlated with the content of hydrocarbon on the surface.Yb_(2)o_(3)coatings exhibited reversible transitions between superhydrophobicity after vacuum treatment and superhydrophilicity after Ar-plasma or heat treatment,linked to hydrocarbon adsorption onto and desorption from the surface.Yb_(2)o_(3)coatings after long-time air exposure and ultra-high vacuum treatment both remained hydrophilic and showed a smaller hydrocarbon content than coatings after vacuum treatment.Al_(2)o_(3)coatings with hierarchical surface structures similar to the Yb_(2)o_(3)coatings showed an increase in WCA to only-170 after the same vacuum treatment,indicating the REO has a much higher affinity for hydrocarbon adsorption than Al_(2)o_(3),and that the content of hydrocarbon adsorbed on the surface of the REO determined the wetting behavior.