No abstract

Microstructural and corrosion characteristic of laser-alloyed TiB2/TiC/Al composite coatings on 6082-T651 aluminium substrate were investigated. Density functional theory was used to study the chemical bonding of TiC and TiB2. The results confirmed a compact TiB2/TiC/Al-coating with low porosity, without any cracks and with good long-term stability against corrosion. Moreover, EIS and CP results confirmed enhanced corrosion resistance of laser-alloyed TiB2/TiC/Al coatings, with lower coating capacitance, increased polarisation resistance and reduced corrosion current density compared to the Al 6082 substrate. Although, all the laser-alloyed coatings experienced pitting attack, the intensity of pitting attack was substantially reduced compared to the substrate material.

This paper deals with the deposition of ceramic powder coating TÍB2-T1C mix with aiuminium powder on the 6082-T651 aiumir)ium äiioy by means of iaser coating. The resuiting coating was studied by means of a microstructurai and microchemicai analysis, Microhardness was measured in the coating and in the substrate area under the coating. A thermodynamic analysis of the system showed the potential existence of aluminium carbide AÍ4C3 in the coating, whereas the EDS analysis indicated a possibie occurrence of aluminium oxycarbides in the coating, containing TÍB2, TiC and AI. An additional thermal analysis explained the existence of two separate exothermic peaks, on the basis of which it couid be inferred that the precipitation of phase MgjS/, which is a typicai precipitate in aluminium alloy 6082, occurred. Microhardness measurements confirmed the differences in the hardness of the coating, resulting from different energy input during the coating process. Due to the thermal effect of the coating process and the rapid cooiing of the coating and the coating-substrate interface, microstructural changes occurred on the substrate surface under the coating The modified microstructure under the coating resulted in reduced hardness, which could be attributed to the use ofthe aiioys in the precipitation-hardened state. Thermal effects ofthe coating process and rapid cooiing contributed to the occurrence of forced dissolution with reduced microhardness.

In the present work, laser surface remelting (LSR) was carried out on C45 carbon steel using an Nd:YAG pulse laser. The effect of process parameters, such as different laser pulse durations and the absence or presence of a graphite absorber, on the microstructure, remelting depth, and microhardness was examined. In most cases, the graphite coating enhanced the laser energy absorption into the surface, resulting in greater depths of the remelted zone (RZ). RZ depth increased ranging from 8 % to 350 %, depending on the laser pulse duration. An increase in the surface microhardness by a factor of 2.6 was achieved in comparison with the substrate material microhardness, namely 559 HV 0.05 versus 211 HV 0.05. Concurrently, the LSR treatment parameters were also investigated using the in process generated acoustic emission (AE) signals. AE characteristics, such as AE peak amplitude, signal duration, count, and energy, were evaluated. A correlation of the AE characteristics was established for the various LSR treatment parameters. The LSR treatment classification results confirm the feasibility of using AE in combination with machine learning (ML) for monitoring LSR and the resulting surface properties of the hardened material.

No abstract