Study On Defect Detection Method Of Magnesium Hydroxide Flame Retardant Material

Magnesium hydroxide flame retardant material is a high thermal stability,safe and non-toxic new flame retardant materials,used in building materials.The flame retardant mechanism is the release of heat-decomposed release of the combination of water,the heat released by the absorption reaction,delay the thermal decomposition of the material while reducing the burning rate of the material to achieve the purpose of flame retardant.However,Because of the different thermal expansion coefficient of the flame retardant and the matrix of the material,it is easy to form a columnar crack at the junction of the matrix.The crack initiation,expansion and accumulation will reduce the service life of the structure,and the crack will make the magnesium hydroxide flame retardant difficult to release the combined water when heated.So the crack increases fire risk of materials and endanger public security.Existing studies have focused mainly on the performance of flame retardant materials and lack of the in-house defects detection during service.In this paper,the internal defects of magnesium hydroxide flame retardant materials were detected by ultrasonic wave,and the detection mechanism was studied.The general rules of ultrasonic testing of the defects of flame retardant materials were obtained.This paper provides theoretical basis for effective analysis of fire risk of flame retardant materials.It is of great significance to reduce fire losses,casualties,and ensure public safety.This article analysis the simulation parameters and boundary conditions of different positions,different sizes and different vertex angles in detail.COMSOL Multiphysics software is used to realize the simulation of ultrasonic testing and Simulation of internal acoustic field.The finite element method is used to establish an ultrasonic model for detecting cylindrical pore defects.The sound field distribution of cylindrical holy defects in magnesium hydroxide flameretardant material was analyzed by ultrasonic method.By using the simulation method,different frequency bands and different geometric parameters of defects are analyzed.Also the optimum range of ultrasonic detection and the general rules of the defect detection of magnesium hydroxide flame retardant materials are obtained.In the experimental verification,considering the simulation results,select the AYUT-8188 S ultrasonic spectrum analysis and flaw detector,which is in accordance with the simulation requirements,and its ultrasonic frequency and echo signal processing method can meet the requirements of experimental verification.The experimental study on the magnesium hydroxide flame retardant material with columnar pore defects in the prefabricated interior was carried out.Comparing with the simulation results,it is verified that the ultrasonic simulation of the internal defect of magnesium hydroxide flame retardant material is simulated.The feasibility of ultrasonic detection on the detection of internal changes of magnesium hydroxide in service process was confirmed.