Effect of Graphene Nanosheets Content on Microstructure and Mechanical Properties of Titanium Matrix Composite Produced by Cold Pressing and Sintering.

Milad Haghighi,Arman Sedghi,Faramarz Djavanroodi,Mohammad Shaeri

doi:10.3390/nano8121024

Abstract

The effect of graphene nanosheet (GNS) reinforcement on the microstructure and mechanical properties of the titanium matrix composite has been discussed. For this purpose, composites with various GNS contents were prepared by cold pressing and sintering at various time periods. Density calculation by Archimedes’ principle revealed that Ti/GNSs composites with reasonable high density (more than 99.5% of theoretical density) were produced after sintering for 5 h. Microstructural analysis by X-ray diffraction (XRD) and a field emission scanning electron microscope (FESEM) showed that TiC particles were formed in the matrix during the sintering process as a result of a titanium reaction with carbon. Higher GNS content as well as sintering time resulted in an increase in TiC particle size and volume fraction. Microhardness and shear punch tests demonstrated considerable improvement of the specimens’ mechanical properties with the increment of sintering time and GNS content up to 1 wt. %. The microhardness and shear strength of 1 wt. % GNS composites were enhanced from 316 HV and 610 MPa to 613 HV and 754 MPa, respectively, when composites sintered for 5 h. It is worth mentioning that the formation of the agglomerates of unreacted GNSs in 1.5 wt. % GNS composites resulted in a dramatic decrease in mechanical properties.

Highlights

Metal matrix composites (MMCs), such as aluminum matrix composites (AMCs) and titanium matrix composites (TMCs), have the potential to improve the physical and mechanical characteristics of metallic materials, such as their modulus and strength [1,2]
The performance of the MMCs extremely depends on the properties of selected reinforcements, such as Young’s modulus, strength, size, morphology, etc. [1]
Carbon nanotube (CNT) and graphene have been extensively considered for their superior qualities as excellent nanofillers [13]

Summary

Introduction

Metal matrix composites (MMCs), such as aluminum matrix composites (AMCs) and titanium matrix composites (TMCs), have the potential to improve the physical and mechanical characteristics of metallic materials, such as their modulus and strength [1,2]. A large number of TMCs have been produced with ceramic reinforcements, such as TiB [7], Al2O3 [8], TiN [9], SiC [10], and TiC [11] These reinforcements improve the mechanical properties and have suitable compatibility, their densities are higher than that of titanium [12]. Many investigations have been focused on the manufacturing of CNT-reinforced titanium-based composites [13,28,29,30], but fewer studies and experiments have been conducted on the mechanical properties and microstructure of TMCs reinforced with graphene. Following the samples’ fabrication, the effects of the volume fraction of reinforcements and time periods of sintering on the microstructure and mechanical properties of TMC were studied. The hardness and shear punch test were employed to measure the mechanical properties of composites

Materials and Methods

Findings

Shear Stress