Prevention & Innovation

The spread of the Covid-19 pandemic has forced us to quickly alter our habits. It is now up to companies to ensure compliance with rules of conduct that allow safe activity. That is why INELCA, aware of the culture of prevention and complying with the Law on the Prevention of Occupational Risks, has incorporated the procedure for action and contingency plan for the Covid-19.

We believe and understand that the multiple measures and actions applied for the safety of the employees, are not temporary measures but a structural change that comes to stay for a long time. And it is in this new framework where innovation can help us and where we have chosen to install temperature detection and access control solutions for early prevention as containment measures. Solutions with high thermographic reliability together with functionalities provided by artificial intelligence providing security, precision and speed. All aimed at a clear and unique objective: the safety of all our employees.

Preparation/Cleaning

For a correct application of any surface treatment, the state of the surface on which it is to be applied is essential.

Because the parts on which the coating is to be applied come from previous processes (stamping, machining, threading, heat treatment, etc…), they must be subjected to cleaning processes prior to the deposition of the coating, otherwise we may find problems of adhesion or even non-coating. This is what is called the preparation phase within the coating processes.

Within the coatings that we apply at INELCA, we can differentiate between two large groups, electrolytic (Zn,ZnNi, ZnFe) and non-electrolytic (Zn flakes), and each of them has a different type of preparation:

Electrolytic:

The preparation phase of electrolytic coatings consists mainly of three stages: chemical degreasing, electrolytic degreasing and pickling.

i)Chemical degreasing: This is an alkaline phase, normally based on soda, responsible for eliminating the oils from the mechanisation of the parts or from the threading processes.

ii)Electrolytic degreasing: This is an alkaline phase, normally based on soda, in which the cleaning effect of the chemical degreasing is added to the mechanical action due to the generation of gas on the surface of the part. This gas is generated by a chemical reaction when an electric current is applied. Thanks to this mechanical action, it is possible to clean up oil residues occluded in the pores of the parts.

iii)Pickling: This is an acidic phase in which metal remains and oxides present in the parts are eliminated, both those that come from natural oxidation and those that may be produced in heat treatments.

In this phase the intermediate coatings for storage that the pieces can have are also eliminated.
The most common acids used in this phase are hydrochloric or sulphuric, to which inhibitors are added to prevent over-attacking of the parts and to minimise possible hydrogen embrittlement.

Zn flakes:

Zn flakes processes, to avoid hydrogen embrittlement processes, have a different preparation. The most common consists of chemical degreasing and shot blasting.

i)Shot blasting: Mechanical cleaning process that consists of projecting abrasive material onto the parts.

Corrosion tests II: Most common types of tests

Imagen para enseyosde corrosión INELCA SLU

In the previous instalment of this publication we saw the definition, purpose and limitations of corrosion tests, in this instalment we will discuss the most widespread types of corrosion tests used to test metal parts coated with sacrificial metals such as Zn, ZnFe, ZnNi and Zn flakes.

SST:

The initials of this test correspond to the Salt Spray Test, currently it is perhaps the most extensive test to evaluate the quality of coatings deposited on steel parts. It consists of introducing the pieces to be tested in a chamber that is filled with mist by means of a nebulizer formed from a solution of distilled water with 5% NaCl (salt), with humidity, temperature and pH of the chamber under standardized parameters. The permanence within the SST will depend on the type of coating to be tested and the specification established by the end user of the parts. During the test, which can go from 24 h to 3000 h or more, the condition of the samples is evaluated every 24 h, and both the corrosion of the coating (WR: white rust) which will appear first, and the corrosion of the steel (RR: Red rust)

Climatic tests:

As we discussed in the previous instalment, corrosion tests cannot be correlated with the useful life of the piece-coating assembly, in order to bring the time of use and test relationship closer several years ago the automotive sector began to specify climatic tests on treated parts. For this, each manufacturer defined a unique test cycle tailored to their needs, thus creating another type of corrosion test: Climate Tests. These tests consist of cycles of usually 24 hours (1 cycle) consisting of subjecting the samples to a sequence of climatic conditions of humidity, SST and sudden temperature changes. The permanence of the samples in the climatic test chambers will depend on the applied coating, the specification of the end user and the type of test defined by each OEM, ranging from 1 to 30 cycles or more.

Covid-19 tests

The Inelca staff underwent tests last week, at its facilities in Sant Esteve de Sesrovires, to check if they are affected by Covid-19 and thus ensure the health of each of them. The results have been satisfactory, allowing the activity to continue safely.

In addition, the facilities have been adapted to the health protocols required by the authorities to minimize the risk of contagion and create a safe work space. These protocols require an effort by everyone, but the general attitude towards this new situation is collaborative and positive.

With all these actions carried out, the level and quality of the response is maintained to provide service to our customers who demand metal surface treatments.

ZnNi and Hydrogenation

One of the drawbacks of electrolytically deposited coatings is the possibility of hydrogenation.

In some of the phases of the coating application process, such as pickling or the deposition phase itself, hydrogen formation occurs on the metal surface to be coated as an auxiliary reaction.
This hydrogen, in monatomic form, can diffuse within the metal structure, producing fragility in it.

This monoatomic hydrogen diffused in the structure of the metal to be coated must be extracted, by means of thermal treatments, before it changes to diatomic hydrogen, at which time it is no longer possible to extract it by conventional dehydrogenation methods.

Zinc-nickel, due to the properties of the deposited layer and the deposition characteristics of that layer, has a much less tendency to hydrogenation than other Zn coatings and other alloys.

i) Properties of the deposited layer:
The deposited zinc layer is not very porous, preventing the hydrogen, which may have diffused in the metal structure to be coated, from being expelled if not by means of heat treatments. On the contrary, the zinc-nickel layer is much more porous and allows the possible diffused hydrogen to be evacuated before going to diatomic form.

ii) Deposition characteristics:
In the first moments of the deposition phase of the zinc-nickel coating, a small nickel layer is generated on the surface of the metal to be coated. This nickel acts as a catalyst in the reaction of the passage of monoatomic to diatomic hydrogen, so that, in this way, it does not diffuse within the base metal structure.

Advantages of ZnNi

Among all the surface coatings of zinc and its alloys, zinc-nickel has a number of advantages that makes it the leader:

i) Greater resistance to corrosion: The presence of 12 to 16% Ni in its structure, allows it to acquire the gamma phase, which gives it greater resistance to corrosion in salt spray and in climatic cycles compared to other applications from Zn.

ii) High resistance to wear: The hardness of the coatings prevents them from being damaged in the coating process itself, as well as in subsequent manipulations such as packaging, selections, transport, assembly, etc.

Layer hardness of various coatings:

Zn: 100 HV
ZnFe: 150-200 HV
ZnNi: 500-550 HV

iii) Reduced white corrosion formation: White corrosion in the ZnNi coating appears much less bulky than in other Zn coatings

Imagen corosión recubrimientos niquel

iv) Good stability at high temperatures: The ZnNi deposit is very stable at temperature, even keeping its properties at working temperature up to 200 ºC.

v) Low Hydrogen embrittlement: Due to the characteristics of the layer of the deposit formed, as well as those of the deposition process, ZnNi presents low Hydrogen embrittlement, as already indicated in standards with ISO 4042.

vi) Low corrosion by contact with Aluminum: Due to the difference in oxidation potentials of Zn and ZnNi, the latter has much less galvanic corrosion by contact with Al, which makes it a coating widely used in both the automotive and in other sectors.

Corrosion tests

A corrosion test involves the performance of laboratory experiments that simulate corrosive environments in order to determine the resistance of coated metals under controlled conditions.

The behaviour against corrosion of a metal is a joint property between its own characteristics and that of the environment that surrounds it, so since there is no valid test that covers all possible variables, it is necessary to define laboratory tests with established and controlled conditions , being the results that we will obtain both qualitative and quantitative.

Corrosion is defined as the attack of a metal by reaction with the environment gradually, this phenomenon implies a cost of between 1.5-3.5% of the gross national product. All metals with the exception of some metals such as Gold or Platinum are corroded to a greater extent in contact with atmospheric agents becoming Oxides.

The purpose of the corrosion tests is to be able to evaluate the long-term performance of various metals in an accelerated manner, which allows determining the behaviour of the various metals before the environmental exposure in a reduced time, although the purposes of the corrosion tests can be diverse (compare behaviour of metals and their alloys, selection of materials according to their use, study of materials….) the most important for anticorrosive coatings is to determine the anticorrosive effectiveness of metals deposited on the metal to be protected.

The results obtained in corrosion tests on coated steel parts allow us to compare results of various coatings under controlled conditions, being able to determine which coating behaves better when faced with external agents, but it should be taken into account that a corrosion test does not simulate the actual behaviour to which the conditions of the same are not 100% extrapolated to the actual exposure conditions, but must be used as a means of control according to standards and reproducibility check of the applied coatings.

INELCA opens a new production plant

As part of the company’s expansion and growth plan, INELCA will inaugurate this March a new plant next to the current one, in the same town of Sant Esteve de Sesrovires (Barcelona) where the main plant is located.

With a constructed area of ??2,200 m2, this plant will be a productive complement to the existing one that will help consolidate future projects and allow us to reach the technological challenges that lie ahead with industry 4.0.

INELCA imagen nueva planta producción INELCA imagen nueva planta producción INELCA imagen nueva planta producción

We are cardioprotected company

Imagen desfibrilador INELCA

Committed to the safety of people in the workplace, we have installed a defibrillator to protect the health of our employees currently working at our facilities in Sant Esteve de Sesrovires (Barcelona).

With the installation of the device, 6 people were trained in cardiopulmonary resuscitation (CPR) and defibrillator use.

The company is sensitized with the fact that in our country the risk of cardiovascular accident has a high prevalence. In this way we intend to preserve the well-being of the employees and of all the people who visit the facilities.

We believe that the current regulation on cardioprotection in work spaces should be modified and the installation of these devices in any work environment, regardless of the volume of employees, should be mandatory.

This action, clearly of improvement, can make the difference between saving or not saving a life because it allows a quick action in case of emergency.

INELCA, SLU
Metal surface coating
Electrolytic coatings

 

Types of corrosion

Imagen trenes corrosión Inelca

Corrosion is defined as the deterioration of a material when interacting with its environment, the metal loses or decreases its physical and / or chemical properties. The corrosion process is accelerated by factors such as oxygen, humidity, temperature, chemicals and the change in the physical-chemical composition of the material.

Through the galvanizing process, a layer of zinc that acts as a sacrificial metal is deposited on the surface of the steel.

The different types of corrosion that occur in a steel treated with a coating of Zn and its alloys are presented below:

  • White corrosion or Zinc oxide: Zn + O2 à ZnO

Zinc is a very durable coating that acts as a sacrificial protection of steel, as it corrodes more slowly. White corrosion is a substance of that colour that can form on zinc when exposed to oxidizing environment. Optimum storage conditions are vital so that their properties are not affected.

  • Red corrosion or Iron corrosion: Fe + O2 à FeO

When the base metal is in contact with oxygen it oxidizes easily. This phenomenon causes iron to lose its properties and become fragile and brittle. That is why it is necessary to protect it by coatings.