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New generation of protective coatings alternative to hard chrome

Final Report Summary - HARDALT (New generation of protective coatings alternative to hard chrome)

Executive Summary:
One of the most widely used coatings in the world, is hard chrome as it exhibits unique properties that help prevent wear and corrosion. The annual cost of corrosion alone is estimated to account for 3.1% of the world’s Gross Domestic Product (GDP). Protective coatings help to reduce the cost of these deleterious mechanisms and thus are popular engineering solutions. However, hard chromium faces many problems: EU restrictions due to the use of hexavalent chromium; health issues for the plating industry personnel due to associated cancers; functional defects of the coatings; and, the low current efficiency in plating. There is therefore an urgent need to find an alternative which was the ultimate aim of HardAlt project.
HardAlt is a successful project within the EU Seventh Research Framework Programme (FP7) and lies specifically under the Research for SME Associations funding scheme. 12 partners from seven different countries participated in this 3 year project that has as a primary target to develop a new alternative to hard chrome coatings utilizing electrodeposition techniques. Thus, five SME associations subcontracted five RTD performers and two SMEs in order to acquire for them the necessary technological knowledge for their members. The aim was to eliminate the use of hard chromium plating across the European electroplating industry by delivering a suitable substitute, which will be based on nano structured Ni-P and Ni-P composite coatings (with, for example, SiC, MWCNT and B4C as reinforcing nanoparticles). The successful outcome of the HardAlt project could lead to the reduction or even elimination of the use of hexavalent chromium in the electrodeposition industry thereby circumventing EU legislation.
Developed pulse current HardAlt composite coatings have improved functional properties as compared to hard chrome The hardness of the as plated coatings reached values of 850-900 HV, while heat treatments (HT) resulted in the further increase of hardness achieving values of 1300 HV. Regarding the tribological properties of developed coatings, depending on the applied conditions (dry, lubricating or corrosive), obtained CoF and wear rates were similar or better in comparison to hard chrome in most cases. Regarding corrosion resistance, delivered HardAlt coatings showed similar or better results. Therefore, it is worth noting that HardAlt coatings show great potential as alternatives to hard chrome coatings in specific applications, thus paving the way for additional testing in other applications, as well as industrial up-scaling of HardAlt technology. Finally, the database for producing Ni-P coatings covering a wide range of possible applications has been created. Of significant benefit is the customization of the HardAlt coatings to the needs of each application whilst using the same bath thereby leading to savings in raw materials and the minimizing of waste from the electroplating industry.
The key program deliverable may be defined as the integrated electroplating process of applying the HardAlt coatings that could be used as alternatives to hard chromium coating along with the training activities that will take place among the members of SME-AGs partners. An integrated process is defined as the ability to apply the innovative coating in consecutive batches in the production line of the electroplating industry SMEs with adequacy in raw materials. The project was implemented over a period of 36 months and the partners have decided to continue this research after the finalization of the project.


Project Context and Objectives:
The total annual estimated direct cost of corrosion, not including wear damage, in the world is estimated at about 3.1% of the world’s Gross Domestic Product (GDP). Protective coatings serve to prevent wear and corrosion and thus reduce the total loss from corrosion and wear. Hard chromium plating is one of the most widely used techniques for production of such coatings. However, hard chromium faces many problems: EU restrictions due to the use of hexavalent chromium, health issues for the plating industry personnel due to cancer cases, functional defects of the coatings and low current efficiency. Thus, there is an urgent need to substitute chrome plating with an alternative that could provide the same or even enhanced benefits that chrome has, without causing the above problems.
The target of the project is to eliminate/reduce the use of hard chromium plating in European electroplating industry by delivering a suitable alternative, which will be the innovative electrolytic nano-structured Ni-P and Ni-P matrix composite coatings reinforced with (nano)particles such as SiC, B4C and MWCNT. The successful outcome of the HardAlt project will lead to the reduction or even elimination of the use of hexavalent chromium in the electrodeposition industry and the coatings developed will not be subjected to these EU legislations. As HardAlt coatings will present equal or even enhanced functional properties compared to hard chrome, they will be adopted by the metal working industry in applications where wear and corrosion resistance is of crucial importance. Ni-P composite coatings with a wide range of properties can be produced by the appropriate imposition of electroplating parameters and applying a thermal treatment where necessary using the same current infrastructure has resulted in new coatings meeting the needs of a large number of applications where hard Cr is used. Significant benefit will be the customization of the HardAlt coatings to the needs of each application using the same bath leading to raw material savings and the minimization of waste from the electroplating industry.
The key program deliverable may be defined as the integrated electroplating process of applying the HardAlt coatings that will be used as alternatives to hard chromium coating along with the training activities that will take place among the members of SME-AGs partners. The integrated process is defined as the ability to apply the innovative coating in consecutive batches in the production line of the electroplating industry SMEs with adequacy in raw materials.

The main objectives of the project are:
Development of a 3 times faster and 70% less energy consuming pulse current electroplating technique, compared to hard chromium, for applying Ni-P coatings. This objective will be verified by measuring the electrodeposition time for specified thickness of coatings and calculating the current efficiency based on Faraday's law.
Delivery of a production line for pulse plating Ni-P deposits with hardness >700 HV and wear and corrosion resistance equal to hard chromium. At least 10 items coated with Ni-P will be provides and tested in a series of measurements such as Vickers hardness, corrosion tests, tribological tests.
Development of pulse current electroplating technique for applying Ni-P composite coatings with a high co-deposition rate of reinforcing particles and better functional properties compared to hard chromium. The codeposition rate of reinforcing particles will be determined by EDS-XRF while functional properties will be verified by hardness, wear resistance, corrosion resistance measurements.
Delivery of a production line for pulse plating Ni-P composite coatings with hardness >800 HV and enhanced wear and corrosion resistance compared to hard chromium. At least 10 items coated by Ni-P matrix composite coatings will be provided and tested in a series of measurements such as Vickers hardness, corrosion tests, tribological tests.
Development of appropriate and fast thermal treatment procedure of coatings for further enhancing of their properties (Hardness values higher than 1200 and 1600 HV for Ni-P and Ni-P composite coatings, respectively). This objective will be verified by providing at least 10 thermally treated items coated by both Ni-P and composite Ni-P deposits and testing them in a series of measurements such as Vickers hardness, corrosion tests, tribological tests.

Project Results:
Within WP1 the main objectives were to generate data on the overall specifications and requirement of the HardAlt coatings and to translate these into specifications of the components and processes for the production line of the coatings. To achieve this all the partners have been actively involved and the SME-AGs especially, contributed in the section on product development by providing all the necessary data based on their experience. Partners CERTH, PoliMi, Asfimet and the SME partners that are related with the field of electroplating collaborated to create the section on the generation of specifications related to the electroplating equipment and all operational parameters. Furthermore, the partners CERTH, PoliMi, CETRI and SEA collaborated on the generation of specifications on Ni-P and Ni-P composites electroplating baths, chemicals, additives and other components that will be used during the electrodeposition process. Finally, the UoS and Falex set all the specifications requested for reliability test methods as well as the field trials.
In WP2, and more specifically in Task 2.1 the specifications related to the substrate pre-treatments prior to the electroplating procedure were determined. Concerning the kind of substrate material it was agreed to use two types of specimens: carbon steel as a basic substrate and aluminium as a hard to plate metal. Thus, appropriate substrate pre-treatment processes that will be applied prior to electrodeposition were developed. Subsequently, the optimum electrolytic parameters for direct current plating of Ni-P coatings in terms of high property performance and low internal stresses have been defined. More specifically, PoliMi and CERTH have developed different Ni-P bath formulations and their composition was optimized to obtain low and high P alloys. Both sulphate based (W-bath) and sulphamate based (S-bath) baths were developed with suitable combinations of additives, working temperature, pH and current density. Ni-P coatings with P concentrations from 3 to 18 % have been electroplated with hardness values ranges from 575 to 715 HV. Thermal treatment procedures that lead to the further enhancement of functional properties of plated coatings has been developed by UBrun. Heat treated Ni-P coatings at 400oC for 1h increase the hardness to a range of 955-1110 HV. The tribological study of the coatings showed comparable performance to hard chrome. The best performing Ni-P coatings that qualify for the next phase of the HardAlt project have been selected and the corresponding optimized DC conditions recorded.
The first objective of WP 3 was to select reinforcing particles to be used for the electroplating of Ni-P composite coatings. Partners CERTH, CETRI and PoliMi selected nano-SiC, MWCNT and B4C as the best candidates. Subsequently, the distribution of reinforcing particles in the bath has been improved by adding suitable additives and applying ultrasound. The effect of the electrodeposition parameters such as applied current density, working pH, addition of different additives and type and load of nanoparticles on the microstructural and mechanical properties of the composite coatings has been investigated. The optimum electrolysis conditions based on the enhanced functional characteristics of Ni-P composites has been defined. The P content in composite coatings ranged from 3 to 18%. Incorporation of reinforcing particles depended on the electrolysis parameters and type of particles. The best performing Ni-P/SiC, Ni-P/CNT and Ni-P/B4C coatings have been selected and the optimal conditions applied for their production delivered for further investigation under pulse current plating in WP5. The developed heat treatment procedure enhanced the functional properties of composite coatings. The coating's hardness reached a peak of 1360 HV at 400oC. It should be noted that, the first attempts to scale up the process were successful and all the applied production steps can be further scaled in order to achieve the desired dimensions and geometries of a component in a future production line as described in the HardAlt DOW. In WP6 all necessary microstructural, mechanical and tribological characterization tests and measurements of the produced DC pure and composite Ni-P coatings have been performed.
Within WP4 the main objectives are focused on investigating the pulse plating of pure Ni-P coatings with respect to applied current density, pulse frequency and duty cycle and their corresponding effect on the microstructure and functional properties of the coatings. The optimum electrolysis conditions have been determined which resulted in improvement of the tribological and mechanical properties as well as increase in corrosion resistance. Results indicate hardness values of the as plated coatings of 600 - 800 HV depending on the P content and 900 - 1000 HV for annealed samples. The tribological results from the coatings showed a comparable performance to hard Cr. A database of the applied parameters versus properties has been created. The obtained results make it possible to conclude that developed baths can be employed to electroplate Ni-P coatings presenting properties meeting the specification set by the HardAlt project.
In WP5 composite Ni-P coatings reinforced by SiC nanoparticles, MWCNTs and B4C, produced by applying PC electrodeposition techniques have been studied as well the effect of electrodeposition parameters on the microstructural, mechanical and functional properties of the composite coatings. Resulting final coatings are semi-bright, uniform and with hardness of 850-900 HV which increases up to 1300 HV after heat treatment. Regarding the tribological properties of developed coatings, depending on the applied conditions (dry, lubricating or corrosive), obtained CoF and wear rates were similar or better in comparison to hard Cr, while heat treated coatings showed similar or better corrosion resistance. Hence, the HardAlt coatings show a great potential as an alternative to hard Cr coatings for specific applications, thus paving the way for further industrial up-scaling and testing. A data-base of composite Ni-P coatings with applied electroplating conditions and obtained functional properties has been recorded.
In WP6 all necessary microstructural, mechanical, tribological and chemical characterization tests and measurements of the produced PC pure and composite Ni-P coatings have been performed. These results enabled the selection of the best reinforcing materials and the optimal processing conditions in order to achieve the highest property values.
In WP7 the successful electroplating of selected HardAlt coatings on rods for shock absorbers, pistons for actuators, drills and piston rods has been demonstrated. All plated coatings produced are homogeneous, adherent and compact. Pure matrix coatings are shiny, while composite coatings are semi-bright. The first attempts of scaling-up the process were highly successful and all applied production steps can be scaled-up further for larger more complex shapes. A multi-testing approach has been followed in which 50 coated samples were evaluated under experimental conditions that simulate the application of shock absorbers. Under dry conditions the heat treated Ni-P-SiC samples had similar wear resistance to hard Cr coatings. Under lubricating conditions all Ni-P based coatings had a similar wear resistance to hard Cr coatings. Ni-P/B4C and Ni-P/SiC composites applied to demonstrators and real components confirmed the improvement of mechanical properties and wear resistance, providing sufficient corrosion protection of the substrate. In the real component tests, they proved to be a real alternative to hard Cr.
WP8 A number of training materials have been produced during the past three years of the project and these are available to the public through the project’s website and community engagement activities. A total of six (6) training courses, web session and workshops were held during the course of the HardAlt project.
WP9 The HardAlt project has been widely disseminated at more than 50 events, presented at several conferences and 3 scientific papers have been published. The project video’s have been produced and disseminated. All partners have agreed on protecting and exploiting the IPR developed in the project and each partner has defined its own business model and a common business approach.

Result 1: Novel method for utilizing pulse current regime in Ni-P electrodeposition
Type of result: Process/methodology
Description of result:
Ni-P electrodeposition by novel method for utilizing pulse current regime including a “Best Practice” on pulse definition, a database for Ni-P pulse deposition and benefits of pulse plating.

Result 2: Method for utilizing pulse current regime in composite Ni-P electrodeposition
Type of result: Process/methodology
Description of result:
Pulse current electroplating method for Ni-P composite coatings production including a “Best Practice” on pulse definition for dispersed phases, a database for composited Ni-P deposition and benefits of pulse plating in composites.

Result 3: Method for improvement of reinforcing particles dispersion in the plating bath
Type of result: Process/methodology
Description of result:
Method for improvement of reinforcing particles dispersion in the plating bath
Micro-metric reinforcing particles mainly used without applying any special dispersion method. Use of ultrasound cavitation method for the dispersion of nanoparticles and use of dispersing agents.

Result 4: Method for proper annealing of Ni-P coatings
Type of result: Process/methodology
Description of result:
Method for proper annealing of Ni-P coatings and parameters (time and temperature) to achieve the highest level of hardness.


Result 5: Method for proper annealing of composite Ni-P coatings
Type of result: Process/methodology
Description of result:
Method for proper annealing of composite Ni-P coatings and parameters (time and temperature) to achieve the highest level of hardness.


Potential Impact:
Europe is at the heart of a devastating economic crisis and a huge number of European SMEs struggle to overcome global competition. Innovative solutions are needed to help them produce desirable marketable products and reduce operational costs. More specifically in the sector of metalworking and electroplating industry, new and effective techniques of electroplating are needed in order to comply with strict EU legislation and prevent diseases caused by the use of Cr+6. The replacement of hard Cr coatings with Ni-P based alternatives will achieve compliance with existing and forthcoming strict EU legislations, directly saving companies that use HardAlt from closure. The large SME community in Europe (approx. 22,000 electroplating companies) that need a new and improved procedure for electroplating will be able to dramatically upgrade and optimize their products taking into consideration the environment’s protection and workers’ health and safety. In conclusion, the advantages of the HardAlt novel coating process and coated items are so attractive and obvious, that they will be desirable for the end users to buy them and European SMEs will therefore gradually become established as dominant players in the global market.

The expected impacts of the project are as follows:
- Clear economic benefits for the SME-AGs participating in the project, for their members involved in the sector and for third parties involved in exploitation.
- A solution to the problem of compliance with current and upcoming EU restrictions of Cr+6 use in electroplating, saving European SMEs from closure
- Clear economic impact on EU economy from reduction of health expenditures (reduced hospital care) and an increase of exports and decrease of imports
- Clear impact on workers’ health protection (significant decrease of cancer cases thanks to Cr+6 replacement)
- Better quality, cheaper and faster coatings in the aerospace, automotive, energy (oil and gas pipelines and drilling), marine, military and tools’ sectors
- Potential development of new or conforming with existing European standards and norms on electroplating especially with respect to health & safety metalworking protection matters
- Internationalization of SMEs through European co-operation for after project partnerships
- Creation of new employment and job opportunities in the EU with the potential for the formation of new start-up companies usind the new HardAlt coatings

The proposed business model for economic benefit for the SME Associations and the SMEs participating in the project is based on the fact that the 5 participating associations will be the co-owners of the results of the project. The SME Associations believe they lack the capability of developing and directly commercialising the new coating procedure, and therefore they intend to license the resulting IPR to several SMEs in return of royalties.
The SMEs participating in the project were specially selected because of their interest in the relevant technology. In exchange for their contribution to the project's completion, they will use the corresponding IPR for free. SMEs that are members of the associations will be licensed and they will pay to the AGs royalties of at least 7% of the commercial margin they obtain when selling the coated products to the market. EU SMEs that are not AG members will be licensed as well, paying in exchange 12% of the commercial margin of their sales.

The plating costs related to the HardAlt coated cylinders or rollers are estimated as well as a sales plan for 5 years following the end of the project. According to the consortium SMEs, the price for a coated cylinder is around 3000€ and the production rate is 2000 per month. Although the raw materials for the Ni-P baths are more expensive than those of hard chrome, the overall production cost will be lower for HardAlt coatings. This is due to energy savings (3 times higher current efficiency for Ni-P and 5 times less electricity/energy consumption), lower labour cost per unit, a one-step procedure, etc..

List of Websites:
Website:
http://www.hardalt.eu/

Email Address:
hardalt@brunel.ac.uk

Project Co-ordinator:
Dr Brian McKay,

Contact Address:
HardAlt
c/o BCAST,
Brunel University London,
KIngston Lane, Uxbridge,
Middlesex, UB8 3PH
United Kingdom.

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