Laser clad Ni-base alloy added nano- and micron-size CeO2 composites

doi:10.1016/j.optlastec.2007.10.007

Optics & Laser Technology

Volume 40, Issue 5, July 2008, Pages 716-722

https://doi.org/10.1016/j.optlastec.2007.10.007 Get rights and content

Abstract

Micron-size Ni-base alloy (NBA) powders are mixed with both 1.5 wt% (%) micron-CeO₂ (m-CeO₂) and also 1.0–3.0% nano-CeO₂ (n-CeO₂) powders. These mixtures are coated on low carbon steel (Q235) by 2.0 kW CO₂ laser cladding. The effects on microstructures, microhardness and wear resistance of the coating by the addition of m- and n-CeO₂ powders to NBA (m- and n-CeO₂/NBA) have been investigated. Addition to the primary phases of γ-Ni, Cr₂₃C₆ and Ni₃B of NBA coating, CeNi₃ shows up both in m- and n-CeO₂/NBA coatings and CeNi₅ appears only in n-CeO₂/NBA coating. Directional dendrite and coarse equiaxed dendrite are grown in m-CeO₂/NBA coating from interface to central zone, whereas multi-oriented dendrite and fine equiaxed dendrite growth by addition of n-CeO₂. The microhardness and wear resistance of coatings are greatly improved by CeO₂ powder addition, and compared to the addition of 1.0% and 3.0%, 1.5% n-CeO₂/NBA is the best. Hardness and wear resistance of the coating improves with decreasing CeO₂ size from micron to nano.

Introduction

Laser cladding is a hard-facing process that uses a high-power laser beam to melt the feeding material and forms a thin coating with specific quality and low dilution that is perfectly bonded to the substrate. Specially, exploitation of economical laser cladding coatings results in application of this advanced technology [1], [2], [3].

Because of high specific surface energy, small size effect and quantum effects of nano-particle, the research on nano-particle coatings has become more and more prevalent and extended. In addition, metal matrix nano-composites possess a series of benefits, which are advantageous on mechanical properties, high shear strength, strong wear resistance, excellent electric and heat conductivity, homogeneous grain size and anti-aging [4]. As a new surface modification technique, laser cladding could greatly improve wear resistance, corrosion resistance, heat resistance and electrical characteristics of workpiece, which results in economizing many expensive alloys [5], [6].

Cerium and samarium, as rare earth elements (RE), have been applied successfully in many fields, such as metallurgy, electronics and chemical engineering. An area of current interest is the modification of RE to surface engineering. Previous study showed the positive effects of RE in flame spraying, surface chemical treatment and laser alloying. However, there is still very little published information on the application of RE in laser cladding. The effects of rare earth oxides CeO₂ and La₂O₃ on the microstructure and wear resistance of laser-clad nickel-based alloy coatings were investigated by Wang [7]. And the results showed that Ce and La refines the microstructure of laser-clad coatings, reduces the secondary dendrite spacing and the inclusion percentage of the coatings and the microhardness and wear resistance of the clad coatings with CeO₂ is enhanced. Cobalt-based alloy coatings with and without nano-Y₂O₃ particles produced by laser cladding on Ni-based superalloy were studied by Li [8], which shows fine and short dendritic microstructure and columnar to equiaxed transition occurred by adding nano-Y₂O₃ particles and Cr₂₃C₆ and nano-Y₂O₃ act as nucleation sites in the melting pool. But the effects on microstructure and mechanical properties of the laser coatings by addition of nano rare earth oxides, compared to micro rare earth oxides, has not been still reported.

So, CeO₂ has greater contribution in improvement of restraining micro-cracks and increasing microhardness compared with other rare earth oxides, such as Y₂O₃ and La₂O₃. n-CeO₂ also has the prominent effect on enhancing wear resistance of metal matrix compound coatings [9]. Therefore, microstructure, microhardness and wear resistance of m- and n-CeO₂/NBA coatings are comparatively investigated in this work.

Section snippets

Preparation of samples

The substrate is Q235 low carbon steel (Table 1) with the dimension of 80 mm×80 mm×10 mm. Fig. 1 shows distribution and grain size of NBA powders, m-CeO₂ and n-CeO₂. Chemical composition of NBA powder (NiSP475; diameter of 90–130 μm, melting point of 1100 °C) shown in Table 2 and 1.5% m-CeO₂ (diameter of 20–50 μm, melting point of 1950 °C) [10] are mixed up with ethanol in a carnelian bowl and well stirred for 40 min. In addition, NBA powder and 1.0–3.0% n-CeO₂ (diameter of 20–40 nm) are mixed up with

Phases of the coating

As seen in Fig. 2, the primary phases are γ-Ni, Cr₂₃C₆ and Ni₃B in NBA coatings. Addition to the primary phases, CeNi₃ exists in m- and n-CeO₂/NBA coatings and small peaks of CeNi₅ appear only in n-CeO₂/NBA coating. According to Ce–Ni binary alloy phase diagram, CeNi₅ phase is formed at high temperature of 1300 °C. The absorptivity of n-CeO₂/NBA to laser energy is larger than that of m-CeO₂/NBA [11]. So, more CeO₂ particles decompose, which results in formation of CeNi₅ phase during rapid

Conclusions

The followings are concluded in this study:

(1)
Addition to the primary phases of γ-Ni, Cr₂₃C₆ and Ni₃B of NBA coating, CeNi₃ shows up both in m- and n-CeO₂/NBA coatings and CeNi₅ appears only in n-CeO₂/NBA coating.
(2)
Directional dendrite and coarse equiaxed dendrite grow in m-CeO₂/NBA coating from interface to central zone, whereas multi-oriented dendrite and finer equiaxed dendrite grow by addition of n-CeO₂.
(3)
The microhardness and wear resistance of coatings are improved greatly with n-CeO₂ addition,

Acknowledgments

This work was supported by Anhui Provincial Natural Science Foundation (070414182) and Foundation of Anhui Educational Administration (2006KJ071A).

This was also supported by the Korea Research Foundation Grant (KRF-2004-005-D00111).

References (19)

C. Sreedhar et al.
J Mater Process Technol
(2001)
C. Navas et al.
Surf Coat Technol
(2006)
S.-H. Si et al.
J Iron Steel Res, Int
(2006)
K.L. Wang et al.
Appl Surf Sci
(2001)
M. Li et al.
Mater Des
(2006)
B.-K. Jang
Mater Chem Phys
(2005)
Y. Yao et al.
Mater Lett
(2007)
Q. Li et al.
Wear
(2003)
X.-B. Liu et al.
Mater Chem Phys
(2007)

There are more references available in the full text version of this article.

Cited by (71)

Role of micro- and nano-CeO<inf>2</inf> reinforcements on characteristics and tribological performance of HVOF sprayed Cr<inf>3</inf>C<inf>2</inf>-NiCr coatings
2023, Surface and Coatings Technology
The present study investigates the role of micro- and nano-CeO₂ reinforcements on microstructural, mechanical and tribological properties of Cr₃C₂-NiCr coatings deposited using high-velocity-oxy-fuel (HVOF) spray process. A novel blending method involving ultrasonication, magnetic stirring and 3D-tumbler mixing was used to prepare the micro- and nano-CeO₂ reinforced Cr₃C₂-NiCr feedstock powders. Unreinforced Cr₃C₂-NiCr coatings were also prepared for comparison purposes. X-ray diffraction, FE-SEM, EDS mapping, optical microscopy and optical profilometry were used to characterize the coatings. Tribological studies were performed on the coatings using modular ball-on-disc tribometer. The results showed that nano-CeO₂ reinforced coatings yielded considerable reduction in porosity, surface roughness and CoF values while significantly enhancing the hardness and fracture toughness in comparison to the micro-CeO₂ reinforced and unreinforced Cr₃C₂-NiCr coatings. The addition of nanoCeO₂ to the coatings contributed to the microstructure refinement and to the formation of stable tribo-oxide layer, resulting in a lower specific wear rate under identical test conditions. Performance of micro-CeO₂ reinforced coatings was intermediate to that of nano-CeO₂ reinforced and unreinforced Cr₃C₂-NiCr coatings.
Effect of CeSi<inf>2</inf> addition on microstructures of brazed layers and interfacial characteristics of brazed diamonds with Ni–Cr filler alloy
2022, Diamond and Related Materials
The thermal damage of diamond is the key factor restricting the performance of brazed diamond tools with Ni-based filler. Hence, the NiCr filler alloy is modified by adding Ce element to reduce the graphitization and improve the mechanical properties of brazed diamond in this work. The results indicate that the microstructures of brazed layers with NiCr filler containing Ce element are obviously refined, and the brazed layer containing 2 wt.% CeSi₂ shows the better wear resistance with stable friction coefficient curve and low wear loss. Meanwhile, the brazed diamond with NiCr filler containing 2 wt.% CeSi₂ exhibits a higher exposure, and the Cr₃C₂ on its surface is finer, which contributes to reduce the stress concentration and cracks formation at interface between diamond and filler. The Raman spectrum results show that the graphitization of brazed diamond is significantly weakened due to addition of CeSi₂. The NiCr filler brazed diamonds containing 2% CeSi₂ remain relatively complete cutting edges and shapes after grinding test, showing the excellent wear resistance. Moreover, the calculation of elastic properties indicates that the in-situ formed CeNi₃ phase exhibits better ductility and plasticity, but lower hardness, and its formation is beneficial to improve the ductility and plasticity of brazed layer.
Effects of nano-CeO<inf>2</inf> on microstructure and properties of Ni625 alloy prepared by laser cladding
2022, Journal of Alloys and Compounds
Citation Excerpt :
Rare earth element having great chemical activity can react with impurity elements such as sulfur, phosphorus, nitrogen and so on, forming stable high-melting-point compounds, which will rise and be cleaned off the clad layer as molten slag, whilst the rest will disperse in the coatings as inclusions. In the study of Zhang et al. [47], the micro-CeO2/Ni-based alloy coating had directional dendrite and coarse equiaxed dendrite from interface to central zone, whereas nano-CeO2/Ni-based alloy coating had multi-oriented dendrite and fine equiaxed dendrite. These results indicate that the nano-CeO2 as nucleating agent is the better choice than micro-CeO2.
In this study, nano-CeO₂ particles as nucleating agents were incorporated into Ni625 alloy powder by ball milling method, with the aim of inhibiting occurrence of liquation crack during Ni625 alloy laser cladding. The differences in microstructure, electrochemical performance and tribological performance between Ni625 and Ni625 + 0.2 wt%CeO₂ cladding layers were studied and compared. The results from scanning electron microscope (SEM) and electron backscattered diffraction (EBSD) analyses clearly revealed that liquation crack in the lap zone between scanning tracks of the Ni625 cladding layer was caused by successive γ + Laves eutectic structure at the boundary of coarse grains. CeO₂ with high melting point and low Gibbs free energy had good stability, and the two-dimensional disregistry between CeO₂ and Ni625 alloy was 5.9%, which made the nano-CeO₂ particles promote the heterogeneous nucleation of Ni625 alloy. Benefiting from heterogeneous nucleation, the Ni625 + 0.2 wt%CeO₂ cladding layer was without liquation crack and had larger equiaxed zone and finer grains. Moreover, the γ + Laves eutectic structure at grain boundary changed from successive distribution to discrete distribution and its content reduced, which indicated that elemental segregation of Mo and Nb during solidification was improved. The results of electrochemistry, microhardness and friction wear tests showed that the Ni625 + 0.2 wt%CeO₂ cladding layer had large charge transfer resistance, higher microhardness and less wear mass loss, which signified that it had better corrosion resistance and wear resistance.
Improving the properties of remanufactured wear parts of shield tunneling machines by novel Fe-based composite coatings
2022, Ceramics International
With the aim of remanufacturing high-value wear parts of shield tunneling machines, novel Fe-based composite coatings were prepared by collaborative modification with nano-TiC and nano-CeO₂ particles. This work aims to improve the wear properties of Fe-based alloy coatings by regulating the morphology and dispersion of TiC through the addition of different contents of nano-TiC and nano-CeO₂. First, the coatings with different contents of nano-TiC (from 5 wt% to 15 wt%) and nano-CeO₂ (from 1 wt% to 2 wt%) were prepared by laser cladding. Subsequently, the microstructure, phase composition, microhardness, and wear properties of the coatings were examined. Furthermore, the wear morphology and the influence mechanism of nano-particles on the wear resistance of the coatings were investigated. It was found that the addition of nano-TiC eliminates the macro-defects of Fe55 alloy coating. Meanwhile, the morphology and dispersion of TiC particles in coatings were affected by the content of nano-TiC and nano-CeO₂. Specifically, the addition of 1 wt% nano-CeO₂ facilitates to the formation of near-spherical tiny TiC particles with low agglomeration in the coating. Therefore, the Fe55 + 10 wt% nano-TiC+1 wt% nano-CeO₂ coating exhibits the best wear property among all the prepared Fe-based coatings. This paper provides theoretical guidance for the preparation of the modified Fe-based coating with excellent wear resistance.
Microstructure and mechanical behavior of the laser synthesized composites modified by micro/nano scale rare earth oxides
2022, Journal of Alloys and Compounds
Citation Excerpt :
Owing to the specific scale effect of the nanomaterials, they always demonstrate unusual behaviors, compared with the micro-scale materials. Hence, some nano-scale REOs have also been used in LC with satisfactory results obtained [31,33,34]. For example, multi-oriented dendrite and finer equiaxed dendrite formed in the laser cladded Ni-based alloy coating with 1.5 wt% nano-CeO2 addition, and higher micro-hardness and wear resistance were obtained compared with the coating with micro-CeO2 [34].
Micro- and nano-scale rare earth oxides (REOs) modified composites were fabricated by laser scanning the preplaced materials, similar to the process in selective laser melting (SLM). To conduct the comparative study on the effect of different REOs, single-layer composites were prepared on Ti-6Al-4V alloy with Ni60A+ 10 wt% B₄C mixture as the basic material and different REOs as the additives. Experiments with micro- and nano-scale REOs (Nd₂O₃, La₂O₃) demonstrated benefits in refining the microstructure, improving both the micro-hardness and wear property of the composites, amongst which the nano-scale REOs showed better performance. Compared with the composite without REOs addition, the composite modified with 1 wt% nano-La₂O₃ exhibited the finest microstructure. The mean micro-hardness increased by ~36.0% from 1058 HV_0.2 to 1439 HV_0.2, and the wear resistance was improved by 38.5% based on the wear volume loss. The better refining effect of the nano-scale REO was mainly attributed to the small particle size, which was more dispersive in the preplaced materials for increased nucleation. This study is not only useful for surface strengthening of titanium alloys, but also provides inspiration for fabricating bulk composite materials with suitable REO additives.
Laser nano-technology of light materials: Precision and opportunity
2021, Optics and Laser Technology
This review discusses the main factors of the formation mechanism of the laser fabricated nano-materials, focusing on the precision microstructures, mechanical properties, biocompatibility, also the research status. Laser nano-technology (LNT), that is, the precision nano-particle/structure/texture can be produced in the light alloys under an action of the laser beam, which can effectively improve the properties of the light alloys, mainly including the laser cladding (LC), selective laser melting (SLM) and laser shock peening (LSP) nano-technology. The trend of development of LNT is discussed, which includes: the preparation of the nano-gradient, the amorphous, the quasicrystalline light materials, the smart nano-materials, the connection of LNT and other techniques. Taking full use of the opportunities for the nano-materials produced by LNT to enlarge the applications of the light alloys also overcome the series of the scientific/technological issues in the coming future.

View all citing articles on Scopus

View full text

Laser clad Ni-base alloy added nano- and micron-size CeO2 composites

Abstract

Introduction

Section snippets

Preparation of samples

Phases of the coating

Conclusions

Acknowledgments

J Mater Process Technol

Surf Coat Technol

J Iron Steel Res, Int

Appl Surf Sci

Mater Des

Mater Chem Phys

Mater Lett

Wear

Mater Chem Phys

Laser clad Ni-base alloy added nano- and micron-size CeO₂ composites