Published at : 28 Jun 2023
Volume : IJtech
Vol 14, No 4 (2023)
DOI : https://doi.org/10.14716/ijtech.v14i4.4240
Riyanto | Department of Chemistry, Faculty of Mathematics and Natural Science, Universitas Islam Indonesia, Jl. Kaliurang KM 14,5, Sleman, Yogyakarta, 55584, Indonesia |
Muhammad Malthuf Jazuli | Department of Chemistry, Faculty of Mathematics and Natural Science, Universitas Islam Indonesia, Jl. Kaliurang KM 14,5, Sleman, Yogyakarta, 55584, Indonesia |
Imam Sahroni | Department of Chemistry, Faculty of Mathematics and Natural Science, Universitas Islam Indonesia, Jl. Kaliurang KM 14,5, Sleman, Yogyakarta, 55584, Indonesia |
Muhammad Miqdam Musawwa | Department of Chemistry, Faculty of Mathematics and Natural Science, Universitas Islam Indonesia, Jl. Kaliurang KM 14,5, Sleman, Yogyakarta, 55584, Indonesia |
Nahar Cahyandaru | Borobudur Conservation Office, Jl. Badrawati, Borobudur, Magelang, Central Java, 56553, Indonesia |
Endang Tri Wahyuni | Department of Chemistry, Faculty of Mathematics and Natural Science, Universitas Gadjah Mada, Jl. Sekip Utara BLS 21, Bulaksumur, Sinduadi, Mlati, Sleman, Yogyakarta, 55281, Indonesia |
This study aims to conserve the underwater
cannonball before storing it in a museum. Removing the
protective crust of iron artifacts without the
correct and proper method can cause rapid corrosion. To prevent
damage, artifacts must be conserved in the right
solution. Conservation was conducted in four stages during this
research project. The first stage is the identification
of weathering, and the second stage is the analysis
and characterization of the corroded surface using a
microscope, XRD (X-ray diffraction), XRF (X-ray
fluorescence), and SEM (scanning electron microscopy). The third
stage is the passivation/deactivation process, achieved using sodium hydroxide,
soapy water and kaffir lime water. The fourth stage is stabilizing/coating the
iron cannonball underwater heritage materials as soon as possible using
microcrystalline wax to prevent further corrosion. This stage should
solve the conservation problems associated with the object so
that the object can last for a long time. Dry and wet-activated corrosion
was characterized by applying XRD to the obtained mineral akageneite. The
akageneite minerals were actively corroded and contained high concentrations of
Cl atoms revealing dry and wet activated corrosion of 66.60% and 64.96%,
respectively. After being conserved with several steps and NaOH, soapy water
and kaffir lime water, inactive corrosion was observed. Based on the results of
the analysis performed with XRF, the cannonball does not contain Cl, and the Fe
content is 98.99%. The conservation
method used in this research is excellent and appropriate for
conserving cultural heritage materials, including underwater iron
cannonballs.
Cannonball; Conservation; Corrosion; Iron; Materials; Underwater
Indonesia is an
archipelago with thousands of islands that have varied cultures.
That diversity produces variegated cultural
heritage remains, either in the form of objects, structures,
buildings, sites, or other heritage types. Based
on the material aspects, objects associated with cultural heritage are composed of different
materials, including stone, brick, wood, metal, and others. So
that future generations can enjoy the culture in conditions that are whole and
complete, cultural heritage must be preserved. To preserve cultural
heritage, conservation actions are needed (Hamilton,
2010).
As an archipelago country, Indonesia is
also a maritime country with a broad sea region. The
history of the nation of Indonesia reflects the marine culture
which made a long journey from the Malay Archipelago. This area was
an important trade route for a very long time, especially
for the trade of commodity spices (Hamilton, 2010).
The current marine transportation area allows Nusantara to
store a wealth of relics from the past. The richness of the
underwater remains due to the sunken ships (shipwrecks),
which are very many scattered in various locations, is unknown. In
addition to sunken ships, the sea of Indonesia also stores a wealth
of other underwater heritage, such as aircraft and other war remnants.
Economically, underwater relics
are also high-value, and their protection is threatened (Liu et al., 2011). The conservation
method used for underwater relics must pay attention to the
characteristics of materials and weathering that occur. Conserved
underwater relics should also be handled by planning before the adoption, at
the time of appointment, and during transport. Planning the placement
of artifacts after their protection is also a concern of the
methods determined for conservation. The researchers developing methods of
conservation of underwater heritage currently still have work
to continue to do (Cornell and Schwertmann,
2003).
The
most striking feature of iron corrosion in an underwater
environment (sea) is the formation of a
thick concretion. Concrete formed on the iron buried
beneath the seafloor and exposed to seawater. This process
of filling the holes and pores in concretion forms
a cement matrix of iron, which slowly dissolves and
replaces the original calcite matrix (Liu
et al., 2011). During crystallization, in areas with
a low oxygen content, the reaction between the iron ions and
sulfide (S2-) ions occurs due to the sulfate generated
from the formation of iron (II) sulfide (FeS) and the
element sulfur (Liu et al., 2011).
Several
methods have been developed for the conservation of underwater cannonball
heritage, such as cathodic protection (Bethencourt et
al., 2018; Angelini, Grassini, and Tusa, 2013; Heldtberg, Macleod, and
Richards, 2004), aerated and deaerated using NaOH solutions (Kergourlay et al., 2018), using natural
products (Abdel-Karim and El-Shamy, 2022;
Verma et al., 2017; Palou, Olivares-Xomelt, and Likhanova, 2014;
Cano and Lafuente, 2013; Kesavan, Gopiraman, and Sulochana, 2012). Several natural products and chemicals have been
used as green corrosion inhibitors, such as anthill (Myrmecodia
Pendans) extract (Pradityana et al.,
2017); acid medium (Shetty and Shetty, 2017);
malonic acid and succinic acid (Thaha et al.,
2019). The final stage after
corrosion stops on underwater cannonball heritage is coating. Several materials
are often used for coatings, such as wax (Ashkenazi
et al., 2017) and graphene nanocomposite (Kumar
et al., 2022). Some conservation methods that are currently
trending are using natural materials because they are nontoxic, cheap, and
environmentally friendly.
This paper aims to conserve underwater
cannonball heritage. Removing the
protective cover crust from
iron artifacts without the correct and proper
method can cause the artifact to corrode rapidly. To prevent
damage, artifacts must be conserved in the right solution. This
research aims to stop the corrosion process and conserve iron
objects in aqueous alkali solutions, and the potential
corrosion was measured.
2.1. Identification of samples
The object examined was the iron
cannonball underwater cultural remnants taken from the sea of
Batavia/Jayakarta, Indonesia. The identified weathering
rates can be compared by paying attention to every
object experiencing active corrosion, which is characterized
by the emergence of new rust (such as the details
of a fluid). Objects undergoing active corrosion can be grouped and
sequenced by implementing appropriate levels of active corrosion handling. The
identification of the weathering of the underwater iron relics is
observed.
3.1. Identification of sample
The weathering of the
iron relics is observed underwater. The result of the
identification of the sample is shown in Figure 2. Figure 2a-d shows the weathering and corrosion that occurs on an iron
cannonball material through the formation of concretion (a buildup of crust),
and the damages cause the breaking and destruction of the objects.
Figure 2 Weathering and corrosion of the iron cannonball material (a) low, (b)
medium, (c) high, (d) advanced
When iron is exposed to the atmosphere,
the environment forms different iron-oxides, such as magnetite (Fe3O4),
hematite , and maghemite (Cornell and Schwertmann, 2003). At temperatures
higher than 560 °C, the
general sequence of the iron-oxide layer (from the interior to each surface) is
Fe/FeO/Fe3O4/Fe2O3/O2 (Fontana, 2005). The redness of the rust powder
and the presence of many cracks and cavities on the object's surface indicate
an active corrosion process being in progress, causing the continuous loss of
metals, as well as the degradation of the mechanical properties (Selwyn, 2004). The corrosion of iron-based
archeological artifacts immersed in seawater is an electrochemical process
involving anodic and cathodic reactions in an aqueous electrolyte environment.
Biological processes also involve anaerobic bacteria (Liu
et al., 2011). When iron is put into solution, the oxide layer
grows slowly, forming oxide compounds, such as goethite , akageneite , and lepidocrocite (Balos, Benscoter,
and Pense, 2009; Barrena, De-Salazar,
and Soria, 2008; Neff et al.,
2006a; 2006b; 2005; 2004; Cornell and Schwertmann, 2003; Balasubramaniam, Kumar, and Dillmann, 2003).
3.2. Characterization
of the surface corrosion of iron cannonball materials immersed in water using a
handy microscope
The results of the analysis
and characterization of the objects obtained using a handy microscope are shown
in Figure 3. Figure 3 can show the presence of corrosion on the immersed iron
cannonball, and the corrosion processes can be distinguished into two types,
namely, dry active corrosion, as shown in Figure 3a and wet active corrosion,
as shown in Figure 3b.
The ongoing problem with iron archeology is the
continued corrosion that occurs after excavation, caused by salt accumulation
during burial. One way to repair iron cultural heritage material is by
immersing the objects in a solution and waiting for chloride ions to spread out
(Selwyn, 2004). The weathering of underwater
relics generally takes place faster than land-based relics. The rate of the
weathering of cultural objects immersed in water can be 5-10 times faster than
that of cultural heritage objects on land (Hamilton,
2010).
Figure 3 Handy microscope images showing the corrosion of the iron cannonball
material by (a) dry active corrosion and (b) wet active corrosion
3.3. XRD characterization of the
surface corrosion of iron cannonball material immersed in water
The result of the characterization of the surface
corrosion using XRD has been shown in Figure 4a and Figure 4b. X-ray spectrometry methods such as
XRD, XRF, and SEM-EDX/EDS are very suitable for the analysis of inorganic
material in the field of conservation and heritage restoration (Emara and Korany, 2016; Theile et al., 2014; Fernandes
et al., 2013; Watkinson, 2013; Van-Grieken
and Worobiec, 2011). Before carrying out conservation, the material to
be conserved must be examined, so it is more appropriate to determine
conservation techniques by considering the costs and resources (Argyropoulos et al., 2013).