Ger be homogeneous. The Diloxanide References oxidation of copper in air begins with formation of Cu2 O, Equation (5), followed by oxidation of Cu2 O to CuO (6) and reaction of CuO to Cu2 O (7). 2 Cu Cu2 O 1 O2 Cu2 O 2 (5) (six) (7)1 O2 two CuO 2 Cu CuO Cu2 OThe oxidation reactions (five)7) can lead to an oxide film with limiting thickness of Cu2 O and continuing growth of CuO [24]. The logarithmic price law is applicable to thin oxide films at low temperatures. The oxidation rate is controlled by the movementCorros. Mater. Degrad. 2021,of cations, anions, or each inside the film, and also the rate slows down rapidly with rising thickness. The linear rate law occurs when the oxide layer is porous or non-continuous or when the oxide falls partly or fully away, leaving the metal for further oxidation. The varying weight adjust inside the thermobalance measurements and surface morphologies assistance the claim that a non-protective oxide layer is formed. The claim that the oxide layer will not be protective is confirmed by the linear raise in weight with time in the QCM measurements. The variations amongst TGA and QCM measurements is usually explained by considering following things. The TGA samples had been created from cold-rolled Cu-OF sheet. The samples were not polished as this would lead to also smooth a surface when when compared with the copper canisters. The dents and scratches noticed in Figures 1 and 11a can act as initiation points and result in uneven oxidation. The QCM samples had been produced by electrodeposition. The deposited layers had been thin and smooth, and no nodular growth was seen. This gives a much more uniform surface when compared with the thermobalance samples. The amount of oxide was larger in the thermobalance measurements than in QCM measurements. For instance, in Figure 1 at T = 100 C, the first maximum corresponds to about 80 cm-2 , whereas in 22 h QCM measurements the weight increase was 237 cm-2 , as shown in Table two. Primarily based on Figure 6 the oxide mass following the logarithmic period is often estimated by Equation (8): m [ cm-2 ] = 0.063 [K] – 17.12 (8) The oxide development through the linear period may be estimated making use of the temperaturedependent rate continual, Equation (9), multiplied by time [s]: k(T) [ cm-2 s-1 ] = 7.1706 xp(-79300/RT) (9)The mass of oxides measured by electrochemical reduction, Table 2, is around the typical about two occasions higher than the mass boost calculated as a sum of Equations (4) and (5). On the other hand, when copper is oxidized to copper oxides, the weight improve measured by QCM is as a result of incorporation of oxygen. As the mass ratio of Cu2 O to oxygen is eight.94 and that of CuO is four.97, the amount of copper oxides on the QCM crystal is larger than what its weight enhance shows. Precisely the same phenomenon was documented in [23]. The mass of oxides detected by electrochemical reduction is about 4 times the mass measured by QCM. The development of your oxide film at higher temperatures proceeds by formation of Cu2 O that may be then oxidized to CuO. Cross-cut analyses in the oxide films show two layers with Cu2 O on the copper surface and CuO on top rated of Cu2 O [257]. The oxidation at low temperatures continues to be not clearly understood [28]. The growth price at the same time as cracking of the oxide film rely on the impurities of copper [8,29]. The usage of common laboratory air as an alternative to purified air has resulted in three to eight times thicker oxides [8]. Within the experiments on the current study at low temperatures making use of OFHC copper with 99.95 purity and regular laboratory air, the oxide morphology sho.