井 敏¹ ，魏 沁^1a ，陈 曦² ，刘静宇^1a ，杨 硕^1a ，王亚男^1a ，孙丛涛³

1. 山东建筑大学 a. 材料科学与工程学院， b. 济南市绿色建材与可再生能源研究重点实验室，山东 济南 250101；

2. 中建八局第二建设有限公司，山东 济南 250100；

引用格式：

井敏，魏沁，陈曦，等. 石墨粉吸波剂对抹灰石膏性能的影响［J］. 中国粉体技术，2024，30（6）：1-9.

JING Min， WEI Qin， CHEN Xi， et al. Effect of graphite powder absorbing agent on gypsum plaster properties［J］. China Powder

Science and Technology，2024，30（6）：1−9.

收稿日期：2024-03-28，修回日期：2024-09-14，上线日期：2024-00-00。

基金项目：国家自然科学基金项目，编号：52378276。

摘要：【目的】 为了低成本制备民用建筑吸波材料，研究不同种类石墨粉对抹灰石膏性能的影响。【方法】 以新型墙体抹灰砂浆—— 抹灰石膏作为研究对象，掺入包括自制的膨胀破碎石墨在内的不同种类列出的低成本石墨粉作为吸波剂，制备石墨-抹灰石膏复合材料；使用X射线衍射仪、扫描电子显微镜、网络分析仪等设备对复合材料的结构、物性、强度和吸波性能进行测试和表征。【结果】 在抹灰石膏中掺入石墨粉，会增加标准扩散度用水量、缩短凝结时间、降低体积密度、降低力学性能、提高吸波性能。相比于天然鳞片石墨和石墨微片，抹灰石膏中掺入8%的膨胀破碎石墨粉可获得最好的吸波性能，在频率为2~18 GHz时，中文（英文，RL）<-5 dB的带宽可达10. 8 GHz，至少有68. 38%的电磁波被吸收，且凝结时间、体积密度和力学性能均可达到国标中对轻质底层抹灰石膏的要求。【结论】 膨胀破碎石墨粉是几种石墨粉中最适合用于民用建筑的低成本吸波剂。

Abstract

Objective With the increasing use of radio， television， mobile phones， computers， artificial intelligence， and 5G technology，our lives have become more convenient， but it has also inevitably resulted in indoor electromagnetic radiation pollution. The increase in electromagnetic density has changed our indoor electromagnetic environment， potentially leading to serious electromagnetic interference， damage to buildings， harm to electrical equipment， and even health risks posed to humans. Therefore， it is necessary to develop building materials to reduce electromagnetic radiation and improve indoor electromagnetic environment.Generally， electromagnetic shielding and absorbing materials are used. Shielding materials only reflect electromagnetic waves without weakening or eliminate them， while electromagnetic wave-absorbing materials convert the energy from electromagnetic waves into other forms such as heat during internal transmission， thereby attenuating the waves and improving building safety.For civil constructions， the requirements for effective electromagnetic wave-absorbing materials should be inexpensive and easy for construction. Graphite， abundant in nature， inexpensive， and exhibiting good electrical and thermal properties， emerges as the main candidate as a wave absorbing agent in construction. Plaster， which is neither load-bearing like concrete nor decorative like architectural paint， is particularly well-suited as a substrate due to its thick application， large surface area coverage，and ease of construction.

Methods To prepare cost-effective wave-absorbing materials for civil buildings， different types of graphite powders， including natural flake graphite， graphite microchips， and homemade expanded crushed graphite， were mixed into gypsum plaster. Their effects on physical properties， strength， and wave absorption were compared. The structure of the graphite-gypsum plaster composites was characterized using X-ray diffraction （XRD）， scanning electron microscopy （SEM）， and vector network analysis.

Results and Discussion XRD analysis showed that the characteristic diffraction peaks of the graphite powder were at 26. 5° and 54. 7°， corresponding to the （002） and （004） crystal planes， respectively， but with variations in peak strengths and widths.Natural flake graphite exhibited strong and sharp diffraction peaks， indicating large grain size and complete crystallization. SEM images confirmed its morphology of thick flakes around 100 um in size， made up of closely stacked layers resembling fish scales. XDR patterns of graphite microchips showed irregular， thin， curled， and fragmented particles with weak， broad diffraction peaks， indicating incomplete crystallization. Expanded crushed graphite， consisting of granular particles with fragmented lamellae， demonstrated intermediate properties between the other two types of graphite. Incorporating graphite powder increased the standard water consumption for gypsum plaster diffusivity. However， the extent of the increase varied depending on the type of graphite powder used. The difference was caused by variations in the specific surface area， particle size， and morphology.Also， their hydrophilicity differences caused by the varying number of surface oxides on the particles contributed to this variation. Natural flake graphite， with its large grain size and compact structure， showed a slow increase in water consumption， while expanded crushed graphite， with smaller particles and a loose lamellae structure， showed a rapid increase due to higher specific surface area and surface oxides after chemical treatment and physical expansion. Graphite powder also accelerated the setting time of gypsum plaster， shortening both the initial and final setting times， which would be disadvantageous for mortar construction. To mitigate this， a retarder must be added to extend the setting time to meet the required standards. For instance， gypsum plaster mixed with 8% expanded crushed graphite powder had an initial setting time of only 20 minutes. However， after adding 0. 1% wt citrate retarder， the initial setting time was extended to 115 minutes， and the final setting time to 240. 5 minutes， meeting the GB/T 28627 standards. The addition of graphite powder reduced the bulk density of gypsum plaster. When 10% natural flake graphite，10% microchips with particle sizes of 30-50 μm， or 5% expanded crushed graphite was added， the bulk density of the gypsum plaster fell below 1000 kg/m3， meeting the density requirements for lightweight base-layer gypsum plaster.Expanded crushed graphite demonstrated advantages as a lightweight filler due to its loose graphite lamella structure and low grain density， which was a result the high-temperature expansion. However， the addition of graphite powder negatively impacted the mechanical properties of the gypsum plaster. The reduction in strength was attributed to increased porosity from higher water consumption and the poor bonding between graphite particles and calcium sulfate crystals. When less than 8% natural flake graphite or expanded crushed graphite was added， the resulting gypsum plasterboards met the GB/T28627 standards for base-layer gypsum plaster， with compressive strengths above 4 MPa and flexural strengths above 2 MPa. At 10% graphite content， the plaster met the GB/T28627 standards for lightweight base-layer gypsum plaster， achieving more than 2 MPa in compressive strengths and more than 1 MPa in flexural strengths. When 8% expanded crushed graphite was added， the tensile adhesive strength reached 0. 45 MPa， complying with the GB/T28627 requirements for both the base-layer and the lightweight base layer gypsum plaster. Graphite powder significantly improved the wave-absorbing properties of gypsum plasterboards. Compared to natural flake graphite and graphite microchips， adding 8% expanded crushed graphite to the plaster yielded the best waveabsorbing performance， achieving a bandwidth of 10. 8 GHz with RL<-5 dB in 2-18 GHz frequency range， with at least 68. 38% of electromagnetic waves absorbed. Moreover， the setting time， bulk density， and mechanical properties all met the GB/T28627 national standards for lightweight base-layer gypsum plaster.

Conclusion Homemade expanded crushed graphite powder is the most suitable， cost-effective wave absorber among the studied

graphite powder for civil construction materials.

Keywords：graphite powder； gypsum plaster； wave absorption； mechanical properties

参考文献（References）

［1］张忠伦，辛志军. 室内电磁辐射污染控制与防护技术［Z］. 北京：中国建材工业出版社，2016.

ZHANG Z L， XIN Z J. Electromagnetic radiation pollution control and protection technology ［Z］. Beijing： China Building Materials Press，2016.

［2］LIU T T， CAO M Q， FANG Y S， et al. Green building materials lit up by electromagnetic absorption function： A review ［J］.Journal of Materials Science & Technology，2022，112：329-344.

［3］朱连诚. 石膏基3D周期结构吸波材料设计及性能研究［D］. 北京：中国建筑材料科学研究总院，2020.

ZHU L C. Design and performance of gypsum based wave-absorbing materials with 3D periodic structure［D］. Beijing： China Building Materials Academy，2020.

［4］郭铮铮. 多级结构石墨烯纳米复合材料的制备及电磁屏蔽性能研究［D］. 西安：西安理工大学，2020.

GUO Z Z. Study on fabrication and electromagnetic shieding properties of multi-layered graphene nanocomposites［D］. Xi 'an：Xi' an University of Technology，2020.

［5］SI T T， XIE S， JI Z J， et al. Synergistic effects of carbon black and steel fibers on electromagnetic wave shielding and mechanical properties of graphite / cement composites［J］. Journal of Building Engineering，2022，45：103561.

［6］LIU Y， JI C， LU L L， et al. Facile synthesis and electromagnetic wave absorption properties of silver coated porous carbon composite materials［J］. Journal of Alloys and Compounds，2021，856：158194.

［7］YU Z， ZHOU R， MA M W， et al. ZnO/nitrogendoped carbon nanocomplex with controlled mor phology for highly efficient electromagnetic wave absorption［J］. Journal of Materials Science & Technology，2022，114：206-214.

［8］LIANG H S， XING H， QIN M， et al. Bamboo-like short carbon fibers@Fe₃O₄@phenolic resin and honeycomb-like short

carbon fibers@Fe₃O₄@FeO composites as high-performance electromagnetic wave absorbing materials［J］. Composites Part A：Applied Science and Manufacturing，2020，135：105959.

［9］苏晓悦，刘平江，张晔，等. 超细石墨复合改性水泥石的导热性能［J］. 中国粉体技术，2023，29（6）：61-71.

SU X Y， LIU P J， ZHANG Y， et al. Thermal conductivity of cement stone modified with superfine graphite ［J］. China Powder Science and Technology，2023，29（6）：61-71.

［10］FANG X， PAN L M， YAO J， et al. Controllable dielec-tric properties and strong electromagnetic wave ab- sorption properties of SiC/spherical graphite AlN microwave-attenuating composite ceramics［J］. Ceramics International，2021，47（16）：22636-22645.

［11］韩彩霞，沈文婷，甘延玲，等. 石墨-石膏基吸波复合材料的制备与性能［J］. 硅酸盐通报，2017，36（8）：2583-2588.

HAN C X， SHEN W T， GAN Y L， et al. Preparation and properties of graphite-gypsum absorbing composite materials ［J］.Bulletin of the Chinese Ceramic Society，2017，36（8）：2583-2588.

［12］金天. 轻质抹灰脱硫石膏砂浆的研究［J］. 江西建材，2022（1）：24-26.

JIN T. Influence of activator on the strength of copper tailings powder composite cementitious materials ［J］. Jiangxi Building Materials，2022（1）：24-26.

［13］TAHIR D，HERYANTO H，IlYAS S，et al. Excellent electromagnetic wave absorption of Co/Fe₂O₃ composites by additional activated carbon for tuning the optical and the magnetic properties ［J］. Journal of Alloys and Compounds，2021，864：158780.

［14］LIU Y， JI C， LU L L， et al. Facile synthesis and electromagnetic wave absorption properties of silver coated porous carbon composite materials ［J］. Journal of Alloys and Compounds，2021，856：158194.

［15］WANG Z， WANG Z， NING M. Optimization of electromagnetic wave absorption bandwidth of cement-based composites with doped expanded perlite ［J］. Construction and Building Materials，2020，259：119863.

［16］SHEN Y N， LI Q H， XU S L， et al. Electromagnetic wave absorption of multifunctional cementitious composites incorporating polyvinyl alcohol （PVA） fibers and fly ash： Effects of microstructure and hydration ［J］. Cement and Concrete Research，2021，143：106389.

［17］吕兴军. 石墨烯/水泥基复合材料制备与吸波性能研究［D］. 大连：大连理工大学，2020.

LU X J. Preparation and microwave absorbing properties of graphene / cement-based materials ［D］. Dalian： Dalian University of Technology，2020.

［18］张萌. 电磁波吸收石膏板的制备与性能研究［D］. 北京：北京工业大学，2014.

ZHANG M. Preparation and properties of electromagnetic wave absorbing gypsum boards ［D］. Beijing： Beijing University of Technology，2014.