Preparation method and application of Si3N4/Fe composite powder capable of improving microwave absorption performance of asphalt concrete pavement

Abstract

The invention discloses a preparation method of Si3N4 / Fe composite powder capable of improving microwave absorption performance of an asphalt concrete pavement. The preparation method comprises the following steps: (1) mixing Si3N4 powder and Fe2O3 powder, and carrying out surface pretreatment; and (2) putting the mixed material of the Si3N4 and the Fe2O3 subjected to surface pretreatment into a tubular furnace, and performing thermal decomposition reaction in a reducing atmosphere to obtain the Si3N4 / Fe composite powder. A magnetic material Fe is introduced into Si3N4, so that the Si3N4 / Fe material has dielectric loss and magnetic loss at the same time, the impedance of Si3N4 / Fe can be matched with air, the impedance matching effect is achieved, the Si3N4 / Fe powder has binary loss performance, the Si3N4 / Fe powder has good microwave absorption performance, the composite powder serves as a microwave reinforcing agent to be applied to asphalt concrete,and the prepared asphalt concrete has relatively strong microwave absorption performance.

Description

technical field [0001] The invention belongs to the technical field of pavement engineering materials, and in particular relates to a Si 3 N 4 Preparation method and application of / Fe composite powder. Background technique [0002] With the continuous increase of road mileage worldwide, the focus of pavement construction has shifted from new pavement construction to pavement maintenance and repair. As a high-efficiency and pollution-free heating method, microwave heating has been studied by many scholars. However, asphalt concrete has poor microwave absorption performance, so researchers try to add microwave-enhanced materials to asphalt concrete to improve the microwave heating performance of asphalt concrete. [0003] At present, microwave-enhanced materials mainly use materials with a single loss mechanism, such as silicon carbide and alumina with dielectric loss properties, carbon black, graphite, and carbon fibers with electrical loss properties, and magnetic media ...

AI Technical Summary

Problems solved by technology

However, the microwave absorption ability of such materials is limited by the frequency, and magnetic media such as magnetic powder or magnetic sand have strong magnetism, although adding them to asphalt concrete will improve its microwave absorption performance, but long-term use will cause corrosion, and Poor water damage resistance and poor durability, which have a great impact on the durability of the road surface

At the same time, the method of adding microwave absorbers as admixtures to asphalt concrete often results in uneven distribution of microwave absorbers in asphalt concrete and a small amount of admixture, which cannot achieve efficient microwave heating performance.

Some scholars add magnetite as a microwave absorbing aggregate to asphalt concrete to enhance the microwave absorption performance of asphalt concrete, but the production area of ​​magnetite is relatively concentrated, and the transportation cost is relatively expensive, which restricts its wide application.

In addition, Liu Ziming and other scholars have studied the microwave healing performance of carbon fiber modified asphalt mixture. The results show that the carbon fiber modified asphalt mixture has good microwave heating performance, but the fiber material is difficult to distribute evenly in the road surface, which will lead to They are overlapped with each other to become conductors, which reflect rather than absorb microwaves

In addition, graphite is an excellent microwave absorber. Although the microwave absorption ability is strong under microwave heating, when the external temperature is too high and the sunshine is strong, graphite concrete, as a good conductor, is easy to absorb heat and heat up, resulting in excessive internal temperature of the concrete. prone to rutting and other diseases

[0004] It can be seen that the existing microwave-enhanced materials will basically have certain defects when added to asphalt concrete. High efficiency microwave absorption and uniform microwave heating are essential