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Address: Garza García, Nuevo León, Mexico

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Papers by Angel Conde

Surface Engineering, 2006

ABSTRACT The laser cladding of diesel engine exhaust valves is an emerging technology that provid... more ABSTRACT The laser cladding of diesel engine exhaust valves is an emerging technology that provides excellent results in terms of the wear and corrosion resistance of the repaired materials. This work focuses on the deposition by laser cladding of Stellite 6 alloy coatings on two different base materials: an AISI 1045 carbon steel and an AISI 304 stainless steel. Following a process optimisation criterion, several of the fundamental laser treatment parameters were varied in order to obtain defect-free coatings with good adherence and minimal dilution. The metallographic structure of the clad material, irrespective of the substrate used, consists of a typical dendritic microstructure in a solid solution of Co. The mechanical strength of the layers was analysed by measuring HV0·1 microhardness and sliding wear behaviour. Laser coatings achieved hardness greater than 500 HV0·1, and presented excellent dry sliding wear behaviour, with a dimensional wear coefficient k one and a half orders of magnitude lower than that of the substrates. A combined oxidation and abrasion mechanism dominated the wear of the Stellite 6 layers, while in the case of AISI 1045 steel substrate, the wear was caused mainly by a surface oxidation mechanism. For the AISI 304 steel, the wear resulted from a combined adhesion, abrasion and plastic deformation mechanism.

Corrosion Science, 1997

... As both phenomena develop at similar rates, only one apparent time constant can be appreciate... more ... As both phenomena develop at similar rates, only one apparent time constant can be appreciated in the Bode plot. ... REFERENCES 1. V. Bello, E. Di RUSSO, Euromat '92: Materials development in rail, tire, wing, hull transportation, vol.1, p. 1-10. AIM, Milano (1992). ...

Surface & Coatings Technology, 2006

Electrochimica Acta, 2006

After a biologically induced corrosion in a 304 stainless steel tube electrochemical tests were c... more After a biologically induced corrosion in a 304 stainless steel tube electrochemical tests were carried out on the affected areas to characterise the nature of attack of the steel covered by the excreted exopolymers. Once the corrosive attack has been developed, the samples were removed from the solution, dried out for 1 month and re-immersed in the same well water

Electrochimica Acta, 2008

The enrichment of copper alloying additions near the surface of sputtering-deposited Al–1.3at.%Cu... more The enrichment of copper alloying additions near the surface of sputtering-deposited Al–1.3at.%Cu, Al–2.7at.%Cu and Al–30at.%Cu alloys is investigated following immersion in nitric acid, which is used commercially as a de-smutting pre-treatment. Corrosion of the alloys is revealed at rates in the range 4–13nmmin−1, leading to enrichment of copper in the alloy surface regions. Enrichments are also generated by nitric acid treatment of AA2024-T3 and AA7075-T6 alloys, with levels similar to those achieved by etching in sodium hydroxide solution. Conventional durations of de-smutting treatments in nitric acid have minor influences on the magnitude of enrichment.

Surface & Coatings Technology, 2005

Surface Engineering, 2006

ABSTRACT The laser cladding of diesel engine exhaust valves is an emerging technology that provid... more ABSTRACT The laser cladding of diesel engine exhaust valves is an emerging technology that provides excellent results in terms of the wear and corrosion resistance of the repaired materials. This work focuses on the deposition by laser cladding of Stellite 6 alloy coatings on two different base materials: an AISI 1045 carbon steel and an AISI 304 stainless steel. Following a process optimisation criterion, several of the fundamental laser treatment parameters were varied in order to obtain defect-free coatings with good adherence and minimal dilution. The metallographic structure of the clad material, irrespective of the substrate used, consists of a typical dendritic microstructure in a solid solution of Co. The mechanical strength of the layers was analysed by measuring HV0·1 microhardness and sliding wear behaviour. Laser coatings achieved hardness greater than 500 HV0·1, and presented excellent dry sliding wear behaviour, with a dimensional wear coefficient k one and a half orders of magnitude lower than that of the substrates. A combined oxidation and abrasion mechanism dominated the wear of the Stellite 6 layers, while in the case of AISI 1045 steel substrate, the wear was caused mainly by a surface oxidation mechanism. For the AISI 304 steel, the wear resulted from a combined adhesion, abrasion and plastic deformation mechanism.

Corrosion Science, 1997

... As both phenomena develop at similar rates, only one apparent time constant can be appreciate... more ... As both phenomena develop at similar rates, only one apparent time constant can be appreciated in the Bode plot. ... REFERENCES 1. V. Bello, E. Di RUSSO, Euromat '92: Materials development in rail, tire, wing, hull transportation, vol.1, p. 1-10. AIM, Milano (1992). ...

Surface & Coatings Technology, 2006

Electrochimica Acta, 2006

After a biologically induced corrosion in a 304 stainless steel tube electrochemical tests were c... more After a biologically induced corrosion in a 304 stainless steel tube electrochemical tests were carried out on the affected areas to characterise the nature of attack of the steel covered by the excreted exopolymers. Once the corrosive attack has been developed, the samples were removed from the solution, dried out for 1 month and re-immersed in the same well water

Electrochimica Acta, 2008

The enrichment of copper alloying additions near the surface of sputtering-deposited Al–1.3at.%Cu... more The enrichment of copper alloying additions near the surface of sputtering-deposited Al–1.3at.%Cu, Al–2.7at.%Cu and Al–30at.%Cu alloys is investigated following immersion in nitric acid, which is used commercially as a de-smutting pre-treatment. Corrosion of the alloys is revealed at rates in the range 4–13nmmin−1, leading to enrichment of copper in the alloy surface regions. Enrichments are also generated by nitric acid treatment of AA2024-T3 and AA7075-T6 alloys, with levels similar to those achieved by etching in sodium hydroxide solution. Conventional durations of de-smutting treatments in nitric acid have minor influences on the magnitude of enrichment.

Surface & Coatings Technology, 2005

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