Wear-resistant nickel-based laser clad coatings for high-temperature applications

The effect of high-temperature processing on laser clad Ni-based coatings is studied. Annealing at 1025°C forms thermally stable framework structures with large chromium carbides and borides. As a result, improved hardness and wear resistance of the coating are maintained when heated to 1000°C. Stabilizing annealing also increases the frictional thermal resistance of the NiCrBSi coating. Under high-speed (3.1– 9.3 m/s) sliding friction, when the surface layer temperature reaches about 500 –1000°С and higher, the wear resistance of the coating increases by 1.7 – 3.0 times. The proposed approach to the formation of heat-resistant coatings is promising, in particular, for a hot deformation tool and other components of metallurgical equipment operating under high thermal and mechanical loads. Such products include crystallizer walls of continuous casting machines. For the walls, the development of laser cladding technology for wear-resistant composite coatings on copper alloys is relevant as an alternative to thermal spraying. The cladding of composite NiBSi-WC coatings of 0.6 and 1.6 mm thickness on a Cu-Cr-Zr bronze substrate heated to 200 – 250°C with a diode laser is considered. The presence of boron causes the formation of the W(C, B) carboboride phase, whose hardness is higher than that of WC in the initial powder. Depending on the thickness of coatings and, accordingly, on the duration of heating and the subsequent cooling, the process of secondary carboborides precipitation from the solid solution can be suppressed (in the “thin” coating) or activated (in the “thick” coating). This leads to a higher wear resistance under friction sliding 1.6 mm thickness coating. © 2019, Institute for Metals Superplasticity Problems of Russian Academy of Sciences. All rights reserved.Institute of Education Sciences, IES: АААА-А18-118020790147-4Russian Science Foundation, RSF: 19-79-00031АААА-А18-118020190116-6The work was supported by the state orders of IMP UB RAS on the subjects “Laser” and “Structure” №АААА-А18-118020190116-6 and IES №АААА-А18-118020790147-4. The study of the evolution of the structure of NiCrBSi coatings during heating was carried out with financial support from the Russian Science Foundation, grant № 19-79-00031. The structural studies were done on the equipment installed at the Plastometriya Collective Use Center of IES UB RAS

Mechanical and Structural Characterization of Laser-Cladded Medium-Entropy FeNiCr-B4C Coatings

Equiatomic medium-entropy alloy (MEA) FeNiCr-B4C (0, 1, and 3 wt.% B4C) coatings were deposited onto an AISI 1040 steel substrate using pulsed laser cladding. Based on an SEM microstructural analysis, it was found that the cross-sections of all the obtained specimens were characterized by an average coating thickness of 400 ± 20 μm, a sufficiently narrow (100 ± 20 μm) “coating–substrate” transition zone, and the presence of a small number of defects, including cracks and pores. An XRD analysis showed that the formed coatings consisted of a single face-centered cubic (FCC) γ-phase and the space group Fm-3m, regardless of the B4C content. However, additional TEM analysis of the FeNiCr coating with 3 wt.% B4C revealed a two-phase FCC structure consisting of grains (FCC-1 phase, Fm-3m) up to 1 µm in size and banded interlayers (FCC-2 phase, Fm-3m) between the grains. The grains were clean with a low density of dislocations. Raman spectroscopy confirmed the presence of B4C carbides inside the FeNiCr (1 and 3 wt.% B4C) coatings, as evidenced by detected peaks corresponding to amorphous carbon and peaks indicating the stretching of C-B-C chains. The mechanical characterization of the FeNiCr-B4C coatings specified that additions of 1 and 3 wt.% B4C resulted in a notable increase in microhardness of 16% and 38%, respectively, with a slight decrease in ductility of 4% and 10%, respectively, compared to the B4C-free FeNiCr coating. Thus, the B4C addition can be considered a promising method for strengthening laser-cladded MEA FeNiCr-B4C coatings. © 2023 by the authors.National Natural Science Foundation of China, NSFC: 52105351; Ministry of Education and Science of the Russian Federation, Minobrnauka: 121102900049-1, 122021000033-2, 122021000036-3This research was carried out within the state assignment of the Ministry of Science and Higher Education of the Russian Federation (themes “Additivity” No. 121102900049-1; “Structure” No. 122021000033-2; and “Spin” No. 122021000036-3) using the equipment of the Collaborative Access Center “Testing Center of Nanotechnology and Advanced Materials” of the IMP UB RAS, and supported by the National Natural Science Foundation of China (Grant No. 52105351)

Influence of Heat Treatment on the Structure and Hardness of the NiBSi Coating

Экспериментальные исследования выполнены на оборудовании ЦКП «Пластометрия» ИМАШ УрО РАН.The effect of high-temperature heat treatment on the structure and microhardness of a NiBSi thermal spray coating was investigated. It was found that annealing at a temperature of 1025 °C, leading to the enlargement of the strengthening Ni3B phase, increases the thermal stability of the coating when heated to 900 °C.Исследовано влияние высокотемпературной термической обработки на структуру и микротвердость NiBSi покрытия, сформированного газотермическим напылением. Установлено, что проведение отжига при температуре 1025 °C, приводящего к укрупнению упрочняющей фазы Ni3B, повышает термическую стабильность покрытия при нагреве до 900 °C.Работа выполнена в рамках государственных заданий для ИФМ УрО РАН по темам «Структура» (№ АААА-А18–118020190116–6), «Лазер» и ИМАШ УрО РАН по теме № АААА-А18–118020790147–4

In-situ Alloying with B4C as a Prospective Method of Strengthening Laser-Deposited CrFeNi Coatings

Настоящая работа посвящена исследованию влияния in-situ легирования карбидом бора наплавленных лазером CrFeNi покрытий. Микроструктура и фазовый состав синтезированных CrFeNi‒B4C покрытий были изучены с помощью сканирующей электронной микроскопии и рентгено структурного анализа, соответственно. Для изучения механических свойств проводили испытания на микротвердость, наноиндентирование и трибологию полученных образцов.The present work is concerned with the research of the in-situ alloying effect of laser-deposited CrFeNi coatings with boron carbide. The microstructure and phase composition of the synthesized CrFeNi‒B4C coatings were studied using SEM and X-ray diffraction analysis, respectively. The microhardness, nanoindentation and tribological tests were carried out to investigate the mechanical prop erties of the obtained samples.Работа выполнена в рамках государственных заданий Министерства науки и высшего образования Российской Федерации (тема «Аддитивность» № 121102900049-1 и тема «Лазер» № АААА-А19-119070490049-8).The work was carried out within the framework of state tasks of the Ministry of Science and Higher Education of the Russian Federation (topic “Ad ditivity” No. 121102900049-1 and topic “Laser” No. AAAA19-119070490049-8)

Laser Cladding and Additive Manufacturing Technologies Using High-Entropy, Ceramic and Multilayer Materials

Рассмотрено получение теплостойких покрытий и деталей из высокоэнтропийных сплавов лазерными наплавкой и выращиванием. Высокоскоростным селективным лазерным плавлением создаются сверхтвердые покрытия на основе карбида и нитрида бора. Предложена комбинированная постобработка изделий аддитивного производства с формированием многослойных тонкопленочных покрытий.The review considers the production of heat-resistant coatings and parts from high-entropy alloys by laser cladding and additive manufacturing. High-speed selective laser melting creates superhard coatings based on boron carbide and boron nitride. A combined post-processing of additive manufacturing products with the formation of multilayer thin-film coatings is proposed.Работа выполнена в рамках государственных заданий ИФМ УрО РАН по теме № АААА-А18-118020190116-6 и ИМАШ УрО РАН по теме № АААА-А18-118020790147-4 при поддержке гранта РФФИ № 20-48­660065 и Свердловской области в части постобработки деталей аддитивного производства с формированием тонкопленочного покрытия. Исследование также поддержано проектом № IRA-SME‑66316 «cladHEA+» по программе M‑ERA. NET, Call 2019‑II в части получения покрытий из высокоэнтропийных сплавов лазерной наплавкой.The work was carried out within the framework of the state tasks of the IFM of the Ural Branch of the Russian Academy of Sciences on the topic no. AAAA18–118020190116–6 and IMASH of the Ural Branch of the Russian Academy of Sciences on the topic no. AAAA18-118020790147-4 with the support of the RFBR grant no. 20-48-660065 and the Sverdlovsk region in terms of post-processing of additive manufacturing parts with the formation of thin-film coating. The research is also supported by the project No. IRA-SME‑66316 “cladHEA+” under the program M‑ERA. NET, Call 2019‑II in terms of obtaining coatings from high-entropy alloys by laser surfacing