TIC/7075铝基复合材料的磨损实验研究

采用原位反应喷射沉积法制备TiC/7075铝基复合材料,并在销一盘式磨损机损上进行摩擦磨损实验研究.通过TEM观察原位TiC颗粒的分布与形貌,并利用SEM观察沉积态组织磨损表面形貌.结果表明:复合材料的耐磨性和TiC颗粒含量及载荷有关,在低载荷(8.9N)状态下,材料的耐磨性随TiC颗粒含量的增加而增强,在高载荷(26...     

Effect of in-situ TiC particulate on the wear resistance of spray-deposited 7075 Al matrix composite

TiC reinforced 7075 Al matrix composites have been fabricated by a melt in-situ reaction spray deposition. The microstructures of spray-deposited alloys were studied using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The dry sliding wear behavior of the alloys was investigated using a pin-on-disc machine under four loads, namely 8.9, 17.8, 26.7 and 35.6 N. It has been found that the wear behavior of the alloys was dependent on the TiC content in the microstructure and the applied load. At a lower load (8.9 N), with increasing TiC content, the wear rate of the alloy was decreased. At a higher loads (26.7, 35.6 N), a spray-deposited 7075 Al alloy exhibited superior wear resistance to the 7075/TiC composites.     

Microstructural evolution of reinforcements in the remelting in situ TiC/Al-12Si composites treated by ultrasonic vibration

Clusters of reinforced particles and long rod-like Al₃Ti particles are usually present in the matrix of in situ TiC/Al alloy composites fabricated via SHS reaction of the Al-Ti-C system in the molten aluminum alloys. In order to improve the properties of the composites, the above issues should be solved effectively. In our research, high-intensity ultrasonic vibration was introduced into the remelting TiC/Al-12Si composites containing clusters of TiC particles and long rod-like Al₃Ti phase to optimize the microstructure of the composites. The results of SEM showed that long rod-like Al₃Ti particles were turned into small blocky ones and large clusters were broken up into small ones. In the meantime, individual TiC particles could be peeled off from the clusters and distributed uniformly in the matrix. An in situ TiC/Al-12Si composite with a homogeneous microstructure was attained successfully. The evolution of the morphology of Al₃Ti phase and the clusters in the ultrasonic field was also discussed.     

Preparation of in situ TiCP/LY12 composite and its microstructure and mechanical properties

Mechanical properties of TiC_P/LY12 Al-based composites prepared by an in situ synthesis method were studied. The micro-structure, morphology, and distribution of TiC_p particles in the LY12 Al alloy matrix were also investigated by XRD, SEM, and HRTEM. The phase composition of the TiC_P/LY12 composites, interfacial structure of TiC particle-to-particle and TiC particle-to-Al matrix, and structure of triple phase among TiC particle, Al₂Cu phase, and Al matrix were also studied. There are no detectable Al₃Ti phases in TiC_P/LY12 composites, and a strong cohesive interface between TiC particles and Al-based alloy matrix was observed in the in situ synthesized TiC_P/LY12 composites. After heat treatment using T6 procedure, it was found that ultimate strength (σ_b), yield strength (σ_s), and Young's modulus (E) of TiC_P/LY12 composites increased but the elongation ratio decreased with increasing of the mass fraction of TiC particles.     

Effect of nano-CeO2 on microstructure properties of TiC/TiN+TiCN-reinforced composite coating

TiC/TiN+TiCN-reinforced composite coatings were fabricated on Ti–6Al–4V alloy by laser cladding, which improved surface performance of the substrate. Nano-CeO₂ was able to suppress crystallization and growth of crystals in the laser-cladded coating to a certain extent. With the addition of proper content of nano-CeO₂, this coating exhibited fine microstructure. In this study, Al₃Ti+TiC/TiN+nano-CeO₂ laser-cladded coatings have been studied by means of X-ray diffraction and scanning electron microscope. X-ray diffraction results indicated that Al₃Ti+TiC/TiN+nano-CeO₂ laser-cladded coating consisted of Ti₃Al, TiC, TiN, Ti₂Al₂₀Ce, TiC_0·3N_0·7, Ce(CN)₃ and CeO₂, this phase constituent was beneficial in increasing microhardness and wear resistance of Ti–6Al–6V alloy.     

Surface modification of titanium alloy with laser cladding RE oxides reinforced Ti3Al–matrix composites

Ti₃Al–matrix composites were prepared by laser cladding of the Al₃Ti/TiB₂/Al₂O₃ pre-placed powders on the Ti–6Al–4V alloy, which can improve the wear resistance of the substrate. With addition of the proper content of RE oxides (nano-Y₂O₃), this composite coating exhibited finer microstructure and better wear resistance. Nevertheless, excessive RE oxides could lead to the production of the micro-crack, and also decrease the temperature of the molten pool leading to the present of the un-melted TiB₂ block, which can significantly decrease the wear resistance of this composite coating.     

In-situ synthesis of TiC/Fe alloy composites with high strength and hardness by reactive sintering

Fe alloy composites reinforced with in-situ titanium carbide(Ti C) particles were fabricated by reactive sintering using different reactant C/Ti ratios of 0.8,0.9,1 and 1.1 to investigate the microstructure and mechanical properties of in-situ Ti C/Fe alloy composites.The microstructure showed that the in-situ synthesized Ti C particles were spherical with a size of 1–3 μm,irrespective of C/Ti ratio.The stoichiometry of in-situ Ti C increased from 0.85 to 0.88 with increasing C/Ti ratio from 0.8 to 0.9,but remained almost unchanged for C/Ti ratios between 0.9 and 1.1 due to the same driving force for carbon diffusion in Ti Cxat the common sintering temperature.The in-situ Ti C/Fe alloy composite with C/Ti = 0.9 showed improved mechanical properties compared with other C/Ti ratios because the presence of excess carbon(C/Ti = 1 and 1.1) resulted in unreacted carbon within the Fe alloy matrix,while insufficient carbon(C/Ti = 0.8)caused the depletion of carbon from the Fe alloy matrix,leading to a significant decrease in hardness.This study presents that the maximized hardness and superior strength of in-situ Ti C/Fe alloy composites can be achieved by microstructure control and stoichiometric analysis of the in-situ synthesized Ti C particles,while maintaining the ductility of the composites,compared to those of the unreinforced Fe alloy.Therefore,we anticipate that the in-situ synthesized Ti C/Fe alloy composites with enhanced mechanical properties have great potential in cutting tool,mold and roller material applications.     

Effect of nano-CeO2 on microstructure properties of TiC/TiN+nTi(CN) reinforced composite coating

TiC/TiN+TiCN reinforced composite coatings were fabricated on Ti?C6Al?C4V alloy by laser cladding, which improved surface performance of the substrate. Nano-CeO₂ was able to suppress crystallization and growth of the crystals in the laser-cladded coating to a certain extent. With the addition of proper content of nano-CeO₂, this coating exhibited fine microstructure. In this study, the Al₃Ti+TiC/TiN+nano-CeO₂ laser-cladded coatings were studied by means of X-ray diffraction and scanning electron microscope. The X-ray diffraction results indicated that the Al₃Ti+TiC/TiN+nano-CeO₂ laser-cladded coating consisted of Ti₃Al, TiC, TiN, Ti₂Al₂₀Ce, TiC_0·3N_0·7, Ce(CN)₃ and CeO₂, this phase constituent was beneficial to increase the microhardness and wear resistance of Ti?C6Al?C6V alloy.     

Dissolution precipitation mechanism of TiC/Ti composite layer produced by laser cladding

Abstract

TiC reinforced Ti matrix composite layer was fabricated by laser cladding of Ti and TiC powder mixture on Ti–6Al–4V alloy. Dissolution precipitation mechanism was speculated to illustrate the formation of TiC dendrite in the composite layer. Microstructure evolution of the composite layer has been explained by this mechanism. The composite incorporates the advantages of external particle composites and in situ synthesised particle composites. This mechanism offers an alternative novel idea for the design of bulk composites as well as composite layers. The composite layer exhibits high hardness and excellent wear resistance.     

Spray processing and wear characteristics of Al-Cu-Al2O3-Pb based composites

The spray deposition process has been employed in synthesis of Al-4.5Cu-10Al₂O₃ and Al-4.5Cu-10Al₂O₃-10Pb based composites. The microstructure and wear characteristics of composites were investigated. The rapid solidification inherent in spray deposition processing resulted in a uniform dispersion of Al₂O₃ and Pb particles co-existing in the matrix of the- primary α-phase. The grain size of the Al-4.5Cu-10Al₂O₃-Pb composite was observed to be higher than that of the Al-4.5Cu-10Al₂O₃ composite in various sections of the spray deposit. The wear rate of composite materials decreased with addition of Pb phase. This behavior is discussed in the light of the microstructural modification induced by spray deposition and the morphology of debris particles on the wear track surfaces. The wear characteristics of the composites are compared with that of the liquid immiscible Al-4.5Cu-10Pb alloy.     

Synergistic effects of TiC and graphene on the microstructure and tribological properties of Al2024 matrix composites

Al matrix composites have attracted significant attention of researchers in recent years due to their lightweight, excellent mechanical and tribological properties. In this study, an Al2024 matrix hybrid composite (AMHC) reinforced with both TiC nanoparticles and graphene nanoplatelets (GNPs) was produced via a route of powder metallurgy. And its microstructure, microhardness and tribological properties are compared with those of unreinforced Al2024 alloy matrix and Al2024 matrix composites reinforced with either only TiC or GNPs. It was found that the distribution of Al₂Cu, TiC nanoparticles and GNPs in the matrix and the wear resistance are significantly improved when introducing both TiC nanoparticles and the GNPs. The wear mechanisms change from the adhesion-dominant wear for Al2024 and the other singly reinforced composites into abrasive-dominant wear for the hybrid composite. The significantly improved wear resistance of the AMHC is attributed to the synergistic effects of reinforcing and self-lubricating of the TiC and GNPs.     

Development of Al3Ti and Al3Zr intermetallic particulate reinforced aluminum alloy AA6061 in situ composites using friction stir processing

Aluminum rich intermetallic particles are potential reinforcements for discontinuously reinforced aluminum matrix composites (DRAMCs). The objective of the present work is to produce AA6061/Al₃Ti and AA6061/Al₃Zr composites using in situ casting technique and applying friction stir processing (FSP) to enhance the distribution and morphology of Al₃Ti and Al₃Zr particles. AA6061/Al₃Ti and AA6061/Al₃Zr DRAMCs were produced by the in situ reaction of inorganic salts K₂TiF₆ and K₂ZrF₆ with molten aluminum. The microstructure was observed using optical and scanning electron microscopy. AA6061/Al₃Ti DRAMC exhibited clusters of Al₃Ti particles while the segregation of needle shape Al₃Zr particles was observed in AA6061/Al₃Zr DRAMC. The prepared composites were subjected to FSP. Significant changes in the distribution and morphology of Al₃Ti and Al₃Zr particles were observed after FSP. The changes in microhardness and sliding wear behavior of AA6061/Al₃Ti and AA6061/Al₃Zr DRAMCs before and after FSP is detailed in this paper.     

Effects of Al2O3 particle reinforcement on the lubricated sliding wear behavior of ZA-27 alloy composites

The present investigation deals with the effect of Al₂O₃ particle reinforcement on the lubricated sliding behavior of ZA-27 alloy. The composites with 3, 5, and 10 wt% of Al₂O₃ particles were produced by the compocasting procedure. Tribological properties of alloy and composites were studied, using block-on-disk tribometer at different specific loads and sliding speeds. The test results revealed that composite specimens exhibited significantly lower wear rate, but higher coefficient of friction than the matrix alloy specimens in all the combinations of applied loads and sliding speeds. The improved antiwear characteristics of the composites were influenced by positive effects of higher frictional heating on compatibility of the composite phases and suppressing micro-cracking tendency. Due to that, effects of reinforcing hard particles were manifested through the reduced wear rate of composites, especially in conditions of higher load, lower sliding speeds and higher Al₂O₃ particle content. In present wear tests, the significant forming of mechanically mixed layers was not noticed, what is confirmed by the SEM microphotographs.     

Tribological behavior and wear mechanisms of Ti-C : H/TiC/TiCN/TiN/Ti coatings when sliding against steel, bronze and aluminum alloy rods

Ti _x%-C : H coatings of differing thicknesses and with various titanium concentrations were deposited on tungsten carbide disks by unbalanced magnetron sputtering. The mechanical properties, microstructure, and adhesion strength of these coating were measured. The tribology properties of the coatings against AISI 1045 steel, AA7075, AA6061 aluminum alloy, and bronze rods were tested by an oscillation sliding test machine with a line-contact wear mode under dry conditions. The microhardness of Ti _x%-C : H coatings increased with an increasing Ti concentration. The optimum coatings are composed of an intermediate layer of TiC/TiCN/TiN/Ti and a top layer of Ti _x%-C : H with x 20%. These coatings have an excellent wear resistance and a low friction coefficient when paired with a carbon steel or copper alloy. These pairs are marked by the mildly wear of the counterbodies of AISI 1045 steel and bronze. The coatings are less suitable for oscillation with the aluminum alloy under dry conditions due to severe adhesion damage.     

Production of TiC reinforced-aluminum composites with the addition of elemental carbon

TiC reinforced Al matrix composites were produced by the additions of elemental carbon to both Al + 4%Ti and Al + 5%Ti alloys. It is shown that the microstructure, phase composition as well as fracture behavior of the composites produced are controlled by the processing parameters, such as temperature, amount of excess carbon and duration. Composite microstructure subjected to 1300 °C for 15 min includes only TiC particles where the fracture occurs in a ductile manner whilst composites subjected to 1200 °C for 30 min contain Al₃Ti and TiC particles which show mixed mode of fracture behavior where Al₃Ti particles resulted in brittle fracture due to their coarser size.     

The investigation of the effect of particle size on wear performance of AA7075/Al2O3 composites using statistical analysis and different machine learning methods

In this study, 7075 - Al₂O₃ (5 wt%) composites with a particle size of 0.3 µm, 2 µm, and 15 µm were developed by hot pressing. The dry sliding wear performance of the specimens was evaluated under loads of 5 N, 10 N, 20 N, 30 N, and at sliding speeds of 80 mm/s, 110 mm/s, 140 mm/s by reciprocating wear tests. The wear tests showed that 7075 - 5Al₂O₃ (15 µm) exhibited the best wear performance. The volume loss of 7075 - 5Al₂O₃ (15 µm) under load of 30 N for sliding speed of 140 mm/s was 37.1% lower than the unreinforced 7075 alloy. The volume loss (mm³) of composites reinforced with the particle size of 0.3 µm, 2 µm, and 15 µm was 11.62, 9.87, and 8.07, respectively, for load of 30 N and sliding speed of 140 mm/s. An increase in the applied load and sliding speed increased the wear severity by changing the wear mechanism from abrasion to delamination. The analysis of variance (ANOVA) showed that the load was the most significant parameter on the volume loss. The linear regression (LR), support vector regression (SVR), artificial neural network (ANN), and extreme learning machine (ELM) were used for the prediction of volume loss. The determination coefficient (R²) of the LR, SVR, ANN, and ELM was 0.814, 0.976, 0.935, and 0.989, respectively. The ELM model has the highest success. Thus, the ELM model has significant potential for the prediction of wear behaviour for Al matrix composites.     

Synthesis of TiC/Ti–Cu composites by pressureless reactive infiltration of TiCu alloy into carbon preforms fabricated by 3D-printing

The microstructure of dense TiC/Ti–Cu composites fabricated by pressureless infiltration of TiCu alloy into porous starch derived carbon preform produced by 3D-printing has been studied. The reactive melt infiltration was carried out at 1100 °C in a flowing Ar atmosphere and resulted in formation of a composite comprised predominantly of substoichiometric TiC_x (x=0.78), binary intermetallic Ti–Cu phases and residual carbon. SEM analyses revealed a microstructure consisting of a dispersed fine-grained TiC_0.78 (∼7 μm) in a Ti–Cu matrix.     

Particle–matrix interface microstructure of in situ TiCp–AlNp/Al composite

Metal–matrix composites reinforced with sub-micrometre particles of TiC and AlN are made by in situ reaction of CH₄ and NH₃ gases with an Al–6.2Ti–4.6Mg (wt.%) melt, with a range of processing conditions being explored. High-resolution electron microscopy of the particle/matrix interfaces show that in all cases they are clean and well bonded. The orientation relationships between the various types of particle and the matrix are examined. In samples where the Ti is completely consumed by the reaction, the TiC particles are coated with a thin layer of Al₃Ti. The presence of this layer has little effect on the mechanical properties of the composites.     

In-situ production of Fe-TiC composite

A TiC/Fe composite was produced by a novel process which combines in situ with powder metallurgy techniques. The microstructure of the Fe-TiC composite was studied by scanning electron microscopy (SEM) and X-ray diffraction (XRD); with the help of differential thermal analysis (DTA), the reaction path of the Fe-Ti-C system was discussed. The results show that the production of an iron matrix composite reinforced by TiC particulates using the novel process is feasible. TiC particles exhibit homogeneous distribution in the α-Fe matrix. The reaction path is as follows: first, allotropic change Fe_α → Fe_γ at 765.6 °C; second, formation of the compound Fe₂Ti at 1078.4 °C because of the eutectic reaction between Ti and Fe; third, reaction between carbon and melted Fe₂Ti causing formation of TiC at 1138.2 °C; finally, Fe₃C formation due to the eutectic reaction between remanent C and Fe at 1146.4 °C.     

Evaluation of wear characteristics of Al3Tip/Mg composite

The dry sliding wear tests were performed for a novel developed Al₃Ti_p/Mg composite under the ambient temperatures at 25–200 °C and the loads of 25–150 N. The wear rate of the composite increased with increasing the load, but reduced with increasing the ambient temperature. The Al₃Ti_p/Mg composite had relatively lower wear rates than AZ91D alloy under the loads of less than 100 N at 25 °C. At 200 °C, the Al₃Ti_p/Mg composite presented an absolutely higher wear resistance than AZ91D alloy, and the mild-severe wear transition was delayed. These were attributed to Al₃Ti particulates and the mechanical mixing layer formed on the worn surfaces, which hindered the plastic deformation and thermal softening of the matrix. The mechanical mixing layer contained MgO, Fe–Ti–O, Al₃Ti, Mg₁₇Al₁₂ and Mg and thickened with increasing the ambient temperature. The predominant wear mechanisms of the composite were oxidation wear and delamination wear.