@PhDThesis{Silva:2011:MoSuAç,
author = "Silva, William de Melo",
title = "Modifica{\c{c}}{\~a}o da superf{\'{\i}}cie do a{\c{c}}o para
melhorias na ader{\^e}ncia de filmes de DLC",
school = "Instituto Nacional de Pesquisas Espaciais",
year = "2011",
address = "S{\~a}o Jos{\'e} dos Campos",
month = "2011-03-14",
keywords = "carbono tipo diamante, carbonitreta{\c{c}}{\~a}o, difus{\~a}o,
dureza, teste de riscamento, ades{\~a}o, diamond-like carbon,
carbonitriding, diffusion, hardness, scratch testing, adhesion.",
abstract = "Em vista das excelentes propriedades
f{\'{\i}}sico-qu{\'{\i}}micas dos filmes de carbono
tipo-diamante (Diamond like Carbon-\textit{DLC}), atualmente,
existe uma corrida cient{\'{\i}}fica e tecnol{\'o}gica para o
desenvolvimento deste revestimento sobre superf{\'{\i}}cies
met{\'a}licas em geral e, em especial, aquelas {\`a} base de
ferro. A partir do momento em que se alcan{\c{c}}arem melhorias
de ades{\~a}o entre os a{\c{c}}os filmes e \textit{DLC}, estes
se tornar{\~a}o um material para as mais variadas
aplica{\c{c}}{\~o}es nas ind{\'u}strias
automobil{\'{\i}}stica, aeron{\'a}utica, aeroespacial,
biom{\'e}dica etc. Por{\'e}m, devido {\`a} excessiva
tens{\~a}o compressiva residual que normalmente acompanha o
crescimento de filmes de \textit{DLC} e, na grande
diferen{\c{c}}a existente entre o coeficiente de expans{\~a}o
t{\'e}rmica do \textit{DLC} e dos a{\c{c}}os, {\'e}
dif{\'{\i}}cil depositar diretamente filmes de \textit{DLC} com
elevada ader{\^e}ncia. Neste trabalho apresentamos um estudo
sobre a deposi{\c{c}}{\~a}o de filmes de \textit{DLC} sobre os
a{\c{c}}os SAE 6150 e AISI 304 com o intuito de melhorar a
ades{\~a}o entre filme e substrato. Para a prepara{\c{c}}{\~a}o
das amostras foi utilizada a t{\'e}cnica de deposi{\c{c}}{\~a}o
qu{\'{\i}}mica a vapor assistida por plasma DC-pulsado. Em um
primeiro momento, foram realizados processos de
modifica{\c{c}}{\~a}o de superf{\'{\i}}cie do a{\c{c}}o SAE
6150 atrav{\'e}s de diferentes est{\'a}gios de termodifus{\~a}o
de carbono e nitrog{\^e}nio anteriores a deposi{\c{c}}{\~a}o de
filmes. Dentre os dados analisados, as difra{\c{c}}{\~o}es de
raios-X indicaram a forma{\c{c}}{\~a}o de fases de carbetos e
nitretos na superf{\'{\i}}cie no a{\c{c}}o SAE 6150 modificado.
A espectroscopia de espalhamento Raman mostrou que a
modifica{\c{c}}{\~a}o de superf{\'{\i}}cie proporcionou o
surgimento de liga{\c{c}}{\~o}es de carbono com
caracter{\'{\i}}sticas semelhantes {\`a}s encontradas no
\textit{DLC}, e provavelmente isto auxiliou na
obten{\c{c}}{\~a}o de ades{\~a}o entre filme e substrato. A
dureza dos filmes corresponde a aproximadamente 19 GPa. A
ades{\~a}o foi avaliada atrav{\'e}s de teste de riscamento que,
devido ao processo de altera{\c{c}}{\~a}o da
superf{\'{\i}}cie, demonstrou ser superior a revestimentos de
\textit{DLC} depositados por t{\'e}cnicas semelhantes.
An{\'a}lises via EDX demonstraram uma alta
concentra{\c{c}}{\~a}o de carbono nas regi{\~o}es de interface.
Medidas de XPS indicaram a forma{\c{c}}{\~a}o de compostos de
Fe\$_{2,3,4}\$N, Fe\$_{x}\$C\$_{y}\$N\$_{z}\$ e Fe3C nas
primeiras camadas at{\^o}micas da superf{\'{\i}}cie do
a{\c{c}}o SAE 6150. Desta maneira, conseguiu-se identificar que a
carbonitreta{\c{c}}{\~a}o modificou a superf{\'{\i}}cie do
a{\c{c}}o SAE 6150 gerando um gradiente de composi{\c{c}}{\~a}o
at{\^o}mica e uma significativa varia{\c{c}}{\~a}o no perfil de
dureza, onde se pode inferir que existe uma regi{\~a}o
intermedi{\'a}ria com baixa energia interfacial capaz de reduzir
o descasamento de expans{\~a}o t{\'e}rmica na
superf{\'{\i}}cie, proporcionando assim, um filme aderente ao
substrato. Um segundo estudo consistiu na compara{\c{c}}{\~a}o
entre as ader{\^e}ncias de filmes de \textit{DLC} depositados
sobre os a{\c{c}}os SAE 6150 e AISI 304. Foi verificada a
influ{\^e}ncia da varia{\c{c}}{\~a}o de temperatura de
carbonitreta{\c{c}}{\~a}o dos a{\c{c}}os mencionados dentro do
intervalo de 430 a 550ºC. Verificou-se que o a{\c{c}}o SAE 6150
tratado a temperatura de 460ºC apresentou melhor ader{\^e}ncia de
filmes, verificada atrav{\'e}s da maior dist{\^a}ncia de
delamina{\c{c}}{\~a}o do revestimento, enquanto que para o
a{\c{c}}o AISI 304 o mesmo efeito ocorreu para a amostra tratada
a 430ºC. De maneira geral, os resultados das t{\'e}cnicas de
caracteriza{\c{c}}{\~a}o de superf{\'{\i}}cie conciliados com
os tribol{\'o}gicos foram capazes de indicar a
forma{\c{c}}{\~a}o de uma regi{\~a}o de transi{\c{c}}{\~a}o
com propriedades mec{\^a}nicas intermedi{\'a}rias entre o filme
e substrato, o que resultou na obten{\c{c}}{\~a}o de boas
ader{\^e}ncias dos filmes de \textit{DLC} sobre os a{\c{c}}os
estudados. ABSTRACT: Nowadays, because of the excellent physical
and chemical properties of Diamond-like Carbon-DLC films, there is
a science and technology race for the development of this coating
on metal surfaces in general and in particular those based on
iron. From the moment that the research in this area achieves
adhesion improvement between DLC films and steel, it will become
an execellent material for a variety of applications in
automotive, aerospace, biomedical industries. However, due to
excessive residual compressive stress that usually accompanies the
growth of DLC films and the large difference between the thermal
expansion coefficient of the DLC and the steel, it is difficult to
deposit DLC films with high adhesion. We present a study on the
deposition of DLC films on the steels SAE 6150 and AISI 304 in
order to improve the adhesion between film and substrate. The
technique used for sample preparation was chemical vapor
deposition assisted by DC-pulsed plasma. At first, processes were
carried out surface modification of SAE 6150 steel through
different stages of carbon and nitrogen thermodiffusion prior to
film deposition. Among the data analyzed, the X-ray diffraction
indicated the formation of carbide and nitride phases on the
surface of the SAE 6150 modified steel. Raman spectroscopy showed
that the surface modification promoted the emergence of carbon
bonds with similar characteristics to those found in DLC, and this
probably can explain the adhesion obtained between film and
substrate. The hardness of the films was measured at about 19 GPa.
Adhesion was evaluated by scratch test that due to the process of
surface modification, proved superior to DLC coatings deposited by
similar techniques. EDX analysis showed a high concentration of
carbon in the interface region. XPS measurements indicated the
formation in the first surface atomic layers of SAE 6150 steel of
Fe\$_{2,3,4}\$N, Fe\$_{x}\$C\$_{y}\$N\$_{z}\$. Thus, it is
reasonable to identify that the carbonitriding modified of the SAE
6150 steel with a gradient of atomic composition and a significant
variation in the hardness profile, where one can infer that there
is an intermediate region with low interfacial energy that can
reduce the mismatch thermal expansion of the area where received
the DLC coating, in this way provide a adhesive film to the
substrate. A second study was the comparison between the adhesion
of DLC films deposited on SAE 6150 and AISI 304 steels. The
influence of carbonitriding steels temperature variation listed
within the range from 430 to 550º C. It was found that the SAE
6150 treated at a temperature of 460º C showed better adhesion of
films, by the greater distance from delamination of the coating
found it, while for the AISI 304 the same effect occurred for the
sample treated at 430º C. Overall, the results of surface
characterization techniques reconciled with the tribological were
able to indicate the formation of a transition region with
intermediate mechanical properties between film and substrate,
which resulted in achieving good adhesion of DLC films on the
studied steels.",
committee = "Trava-Airoldi, Vladimir Jesus (presidente/orientador) and Corat,
Evaldo Jos{\'e} and Silva, Marcos Dias da and Massi, Marcos and
Moro, Jo{\~a}o Roberto",
copyholder = "SID/SCD",
englishtitle = "Steel surface modification for DLC films adhesion improvements",
language = "pt",
pages = "121",
ibi = "8JMKD3MGP7W/396CU8E",
url = "http://urlib.net/ibi/8JMKD3MGP7W/396CU8E",
targetfile = "publicacao.pdf",
urlaccessdate = "05 maio 2024"
}