Progress in Bio‑inspired Anti‑solid Particle Erosion Materials:Learning from Nature but Going beyond Nature

Solid particle erosion is a common phenomenon in engineering fields,such as manufacturing,energy,military and aviation.However,with the rising industrial requirements,the development of anti-solid particle erosion materials remains a great challenge.After billions of years of evolution,several natural materials exhibit unique and exceptional solid particle erosion resistance.These materials achieved the same excellent solid particle erosion resistance performance through diversified strategies.This resistance arises from their micro/nanoscale surface structure and interface material properties,which provide inspiration for novel multiple solutions to solid particle erosion.Here,this review first summarizes the recent significant process in the research of natural anti-solid particle erosion materials and their general design principles.According to these principles,several erosion-resistant structures are available.Combined with advanced micro/nanomanufacturing technologies,several artificial anti-solid particle erosion materials have been obtained.Then,the potential applications of anti-solid particle erosion materials are prospected.Finally,the remaining challenges and promising breakthroughs regarding anti-solid particle erosion materials are briefly discussed.

Impact of inter-particle collision on elbow erosion based on DSMC-CFD method

In this work,computational fuid dynamics(CFD)is used to study elbow erosion due to a gas-solid two-phase fow.In particular,the direct simulation Monte Carlo(DSMC)method is used to study the impact of inter-particle collision on the erosion behavior.The two-way coupled Euler-Lagrange method is used to solve the gas-solid fow,and the DSMC method is used to consider the collision behavior between particles.The efects of key factors,such as the particle concentration distribution and inter-particle collision,on the erosion ratio are evaluated and discussed.The efectiveness of the method is verifed from experimental data.The results show that the inter-particle collision signifcantly infuences the particle movement path and erosion ratio.When the inter-particle collision is considered,the maximum erosion position is ofset.The erosion model proposed by Oka et al.,who used the DSMC method,agrees best with the experimental data,and the average percentage error decreases from 39.2 to 27.4%.

Particle erosion of infrared materials

Erosion test of some infrared （IR） optical crystals （Ge, ZnS, MgF2, and quartz） was conducted with a number of different erodents （glass bead, and angular SiC, SiO2, Al2O3） by a homemade gas-blasting erosion tester. The influence of impact angle, impact velocity, erodent, and erosion time on the erosion rate and the effect of erosion on their IR transmittance were studied. The dam- aged surface morphology was characterized by scanning electron microscopy, and the erosion mechanism was explored. All of the materials show the maximum in wear versus impact angle at 90°, confirming their brittle failure behavior. It is found that the erosion rate is dependent on the erodent velocity by a power law, and it is highly correlated to the hardness of the erodent. The erosion rate-time curves do not show an incubation state, but an accelerated erosion period followed a maximum erosion （steady state）. The decrease of IR transmittance is direct proportion to the erosion rate. Although the material loss occurs primarily by brittle process, ductile behavior is clearly an important feature, especially for MgF2 and ZnS.

Numerical study of gas-solid two-phase flow and erosion in a cavity with a slope

Gate valve is mainly used to turn on or turn off the pipeline in pneumatic conveying.When the gate valve is fully open,the particles are easy to collide with the cavity rear wall and enter into the cavity,resulting in particles’accumulation in the cavity.The particles in cavity will accumulate between the cavity bottom and the flashboard bottom wall and prevent the gate from turning off normally.Meanwhile,the particles’collision with cavity rear wall will cause serious erosion.Both the particles’accumulation and erosion will cause the poor sealing of the gate valve,further resulting in the leakage of the pipeline system.To reduce the particles’accumulation in cavity and erosion on cavity when the gate valve is fully open,we simplify the gate valve into a cavity structure and study it.We find that adding a slope upstream the cavity can effectively reduce the particles’accumulation in the cavity and the erosion on the cavity rear wall.In this work,Eulerian-Lagrangian method in commercial code(FLUENT)was used to study the gas-solid two-phase flow and erosion characteristics of a cavity with a slope.The particle distribution shows that the particles with Stokes number St=1.3 and St=13 cannot enter the cavity due to the slope,but the particles with St=0.13 enter the cavity following the gas.For St=13,the particles collide with the wall many times in the ideal cavity.Erosion results show that the slope can transfer the erosion on cavity rear wall to the slope and reduce the maximum erosion rate of the wall near the cavity to some degrees.