Nissan has adopted valve seats manufactured using cold spray technology, marking a world-first application in automotive engines. The cold spray technology is being applied by Nissan to its latest 1.5l turbocharged engine, which is exclusively designed for power generation within the third-generation e-Power hybrid powertrain.

The first vehicle to feature the e-Power system, the Qashqai compact crossover, began production at Nissan’s factory in Sunderland, UK, in July.

Valve seat design for new engine

The engine employs Nissan’s proprietary STARC 2 concept, which is able to elevate thermal efficiency to 42% by stabilizing in-cylinder combustion.

A key element of the STARC concept is minimizing airflow turbulence from the intake port into the combustion chamber, thereby generating a strong tumble flow.

In conventional engines, the design of the intake port is constrained by the necessity for press-fitted, sintered valve seats, which limit the ability to optimize port shape for ideal tumble flow. Nissan engineers addressed this challenge by developing a novel valve seat using cold spray technology. This process allows a coating to be directly formed onto the cylinder head surface, eliminating the need for a separate valve seat component and enabling an optimized intake port geometry. Furthermore, compared to similar methods, its higher thermal conductivity enables improved cooling performance around the valves.

The alternative valve seat is produced by spraying dissimilar metal powders at supersonic speed onto the aluminum alloy cylinder head surface, forming a robust and durable coating that adheres strongly without melting the base material.

Cold spray technology

Cold spray technology operates below the melting points of the materials involved, enabling the bonding of dissimilar metals without melting. This process prevents the formation of excessive intermetallic compounds and microvoids (porosity) that are common in traditional fusion welding methods. As a result, cold spray coatings exhibit superior adhesion, durability and reliability.

The process incorporates a specially developed cobalt-free, copper-based alloy with excellent thermal conductivity, in-house nozzles inspired by polishing techniques used in forged mold production, and AI-driven quality assurance systems.

Updates to the e-Power hybrid powertrain

e-Power is Nissan’s electric-drive powertrain, which combines a compact gasoline engine, battery and electric motor. The engine functions solely as a generator, providing electricity to power the motor – delivering a fully electric driving experience without the need for external charging.

In addition to the advanced 1.5-liter turbocharged engine, the latest e-Power adopts a 5-in-1 modular electric powertrain unit which integrates the electric motor, generator, inverter, reducer and increaser into a compact and lighter package. This unit delivers significant improvements in both fuel efficiency and cabin quietness.

In related news, Ford recently announced that it is investing approximately US$5bn across its Louisville Assembly Plant and the BlueOval Battery Park in Michigan to deliver a new pickup and produce advanced prismatic LFP batteries, and has launched its new Ford Universal EV platform and Ford Universal EV Production System

A team of scientists from Ames National Laboratory in the US, operated by Iowa State University, say they have developed a new machine learning model for discovering critical-element-free permanent magnet materials. According to the research, the model predicts the Curie temperature of new material combinations. This adds to the team’s recently developed capability for discovering thermodynamically stable rare earth materials.

The team used experimental data on Curie temperatures and theoretical modeling to train the ML algorithm. “Finding compounds with the high Curie temperature is an important first step in the discovery of materials that can sustain magnetic properties at elevated temperatures,” said Yaroslav Mudryk, a scientist at Ames Lab and senior leader of the research team. “This aspect is critical for the design of not only permanent magnets but other functional magnetic materials.”

Mudryk noted that discovering new materials is a challenging activity because research is traditionally based on costly and time-consuming experimentation. The hope is that using an ML method can save time and resources. The team trained its ML model using experimentally known magnetic materials. The information about these materials established a relationship between several electronic and atomic structure features and Curie temperature. These patterns then provided a starting point for finding potential candidate materials.

The model was tested using compounds of cerium, zirconium and iron. This idea was proposed by Andriy Palasyuk, a scientist at Ames Lab and a member of the research team. He wanted to focus on unknown magnet materials based on earth-abundant elements. “The next super magnet must not only be superb in performance but also rely on abundant domestic components,” he noted.

Palasyuk worked with Tyler Del Rose, another scientist at Ames Lab and a member of the research team, to synthesize and characterize the alloys. They found that the ML model was successful in predicting the Curie temperature of material candidates.

This research is discussed further in Physics-Informed Machine-Learning Prediction of Curie Temperatures and Its Promise for Guiding the Discovery of Functional Magnetic Materials, written by Prashant Singh, Tyler Del Rose, Andriy Palasyuk and Yaroslav Mudryk, and published in Chemistry of Materials.

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An automatic transmission case is a very complex casting incorporating a sophisticated valve body with multiple cross-channels and passages. Often it is necessary to drill through the casting to create these channels, creating cross-drillings. Doing so leaves a hole in the shell, which must be sealed to prevent fluid loss.

A long-time Promess customer uses an electromechanical assembly press (EMAP) to press a steel ball bearing into these holes to seal them. This sealing method worked in previous applications, but on a particular thin-walled transmission case it led to cracking of the housing, unacceptable leakage rates and warranty issues.

The EMAP is an electric servo press instrumented to monitor and precisely control peak force and final position. In this case the user programmed the ball-pressing application to stop at a specific distance, and only the distance was controlled. Neither the dimensions of the ball nor the diameter and surface finish of the hole were held to tight tolerances. As a result, the same level of force could leave the ball in a wide range of positions, which caused leakage and cracking of the thin-walled case.

Faced with unacceptable cracked housings and yield issues, the manufacturer decided to replace the steel ball with a Betaplug expansion plug from The Lee Company. This pre-assembled, two-piece tapered expansion plug has an inner pin and an outer plug body with lands and grooves that bite into the housing during
the installation process.

The Betaplug product is installed in a matching tapered bore that creates a perfect fit, reducing unnecessary expansion and giving a predictable stress level, ideal for brittle materials or thin wall conditions. The installation tool is designed to install the inner pin below flush while staking over the back edge of the plug body.

Assessing the situation
Use of the Betaplug expansion plug eliminated the cracked housing and production yield issues. However, the manufacturer carried over an improper installation specification that created new manufacturing problems – an unacceptable scrap rate, yield issues and damages in the fixturing. The manufacturer contacted Promess, supplier of the EMAP, and The Lee Company. Both companies were asked to examine the complete installation and assembly process and suggest a solution to the high scrap rate.

The Lee Company engineers determined that the Betaplug products were being over-pressed, which produced excessive radial force when the pin moved to expand the plug body and extruded the plug into the installation bore. The manufacturer was reluctant to change the distance-based programming because plugs that were installed successfully were not failing in the field. They were not happy with the scrap rate, but they were willing to accept it.

A proper installation for a Betaplug product should be terminated when the staking is complete, regardless of where the unit is within the bore. The manufacturer’s engineers wanted to install the plug at a fixed point within the bore – where the steel ball plug had performed best – regardless of the optimum staking location. However, in a tight bore this generated the excessive installation force that extruded the Betaplug expansion plug.

Promess engineers recommended that the manufacturer alter its process to measure more than a simple force level or distance. The engineers highlighted the benefit of combining EMAP instrumentation with the sophisticated data processing capabilities of the Promess Motion Controller. This gives the ability
to measure and control absolute force and distance, as well as more complex relationships such as the rate of change between those measurements.

During installation the Betaplug product initially moves as a unit until the lands on the outer plug body begin to dig into the bore. When adequate resistance is achieved, the plug body stops moving but the inner pin continues to move and generates the expansion force that creates leak-tight seals and ensures retention. When the pin is 0.5-0.8mm below flush, the installation tool stakes over the top edge of the plug body.

This transition produces a readily detectable inflection point in the rate of change relationship between press force and distance, making it a simple matter to stop the press when the pin is appropriately inserted into the plug body. The programming can also detect parts that are upside down, sideways, or missing a pin or other component.

Promess engineers and their Lee counterparts performed extensive laboratory testing to validate the new programming. This was done prior to installing the upgraded application in the manufacturer’s plant, where further trials were performed.

Plug and program solve the problem
The new EMAP program and the corrected installation procedure solved the installation yield issues and reduced the scrap rate. It was in fact determined that many of the scrapped parts – previously discarded because the Betaplug products were not inserted to the originally specified distance – were perfectly acceptable and would not have failed in the field. Since the change to the plug and program, over 35 million plugs have been installed and used in the field without any warranty returns for leakage.

Automotive Tier 1 Schaeffler has signed a five-year contract with Norwegian company REEtec for the purchase of rare earth oxides. The aim, says Schaeffler, is to make its electric motors for hybrid modules, hybrid transmissions and all-electric axle drives more sustainable by sourcing rare earth metals from REEtec, which uses a sustainable production process. The partnership will begin in 2024.

“In REEtec, Schaeffler has gained a highly innovative partner that uses a novel and especially sustainable process for the production of pure rare earth elements,” said Andreas Schick, COO at Schaeffler. “Rare earths play an important role in the automotive and industrial segments. Schaeffler is focusing on achieving sustainability along the entire value chain and is systematically gearing its activities to the use of materials produced cleanly and sustainably. Through this partnership, we are also securing our supply of neodymium iron boron magnets for electric motors.”

Based on its proprietary technology, REEtec has been separating rare earths on an industrial scale since 2019. The company’s new plant in Herøya, near Porsgrunn in Norway, will process rare earth carbonates produced by Canada’s Vital Metals.

Nissan and the Japanese Waseda University say they have begun testing and co-developing a recycling process that aims to recover high-purity rare earth compounds from EV motor magnets.

With many EV motors utilizing rare earth materials, the evolution of the recycling process is seen as an important step to aid in reducing the environmental impacts associated with mining and refining operations. As the balance of supply and demand for the rare materials shifts, this can also lead to prices rising or falling.

The first successful pyrometallurgy process was developed by the partnership in March 2020 and negates the need to disassemble EV motors before recovering REEs.

At present, the testing phase has shown that 98% of REEs from the EV motors can be recovered. The latest process is also around 50% quicker than the current method as magnets don’t have to be demagnetized, disassembled or removed.

Both companies will continue to develop the process for practical application, and Nissan will continue to collect metals from the EV recycling process to further develop the company’s recycling system. The duo hopes to begin using the process by the middle of the decade.

The process works by adding carburizing material and pig iron to the motor, which is then heated to a melting point of 1,400˚C. Iron oxide is added to oxidize REEs in the molten mixture. A small amount of borate-based flux is then placed into the mixture to dissolve the rare earth oxides at a low temperature. This borate-based flux is also highly efficient at recovering REEs.

As a result of the process, the molten mixture then separates into two layers, a molten oxide layer (slag) that contains the REEs at the top, and a high-density iron-carbon (Fe-C) alloy at the bottom. The REEs are then recovered.

The company notes that its engineers were able to carry out several development steps at once with the prototype. It states that the additively manufactured alloy housing is lighter weight than a conventionally cast part, and reduces the overall weight of the drive by approximately 10 percent. Thanks to special structures that have only become possible due to additive manufacturing, the stiffness in highly stressed areas has nevertheless been doubled.

“Our goal was to develop an electric drive with the potential for additive manufacturing, at the same time integrating as many functions and parts as possible in the drive housing, saving weight and optimizing the structure,” explained Heilfort. The drive housing was manufactured from high-purity metal powder using a laser metal fusion process (LMF).

Porsche explains that optimization of the electric drive started with the design integration of components such as bearings, heat exchangers and oil supply. This was followed by the computer-calculated definition of loads and interfaces which were then used to calculate load paths. The next step in the virtual development method was optimization of the load paths by integrating the so-called lattice structures. “We were able to expand and improve our software solutions and methods for creating such parts and are now able to virtually implement them in a very short space of time,” noted Sebastian Wachter, specialist in design methodology and topology optimization in the Powertrain Advance Development department.

However, Porsche notes that the extended design freedom offered by additive manufacturing also goes hand-in-hand with specific design requirements. For example, its engineers had to take into account the fact that the work pieces are produced layer by layer. Thus, if there are large overhangs, supporting elements such as ribs needed to be incorporated. This meant it was important to take into account the direction in which the layers would be built up early in the design phase.

With the machine technology currently available, Porsche says printing of the first housing prototype took several days and had to take place in two build processes due to the component size. With the latest machine generations, it says it would be possible to reduce this time by 90 percent, and the entire housing could be manufactured in a single process.

Porsche claims that the weight of the housing parts were reduced by approximately 40 percent due to the integration of functions and optimization of the topology. It points out that stiffness was increased significantly at the same time. Despite a continuous wall thickness of only 1.5 mm, the stiffness between the electric motor and the gearbox was increased by 100 percent due to the use of lattice structures.

The company explains that the use of these honeycomb structures reduces the oscillations of the thin housing walls and thus considerably improves the acoustics of the drive as a whole. The integration of parts made the drive unit more compact, significantly improved the drive package, and reduced the assembly work by around 40 work steps. This equates to a reduction in the production time of approximately 20 minutes. An additional benefit was that the integration of the gearbox heat exchanger into the housing, with optimized heat transmission paths, improved the cooling of the drive as a whole.

Powertrain business Tenneco has produced a new sintered material that has a greatly reduced cobalt content, while still delivering highly wear-resistant qualities. The new material will provide engine and component manufacturers with an alternative to cobalt.

 Manufacturer’s typically rely on using cobalt for applications when wear resistance over a wide temperature range from 0°C to 1,000°C (32°F to 1,832°F) is vital, such as high-performance engine valve seats, turbocharger wastegate bushings and EGR valves.

Gian Maria Olivetti, vice president of global engineering at Tenneco, explained, “Potential material shortages and controversy around cobalt mining, coupled with extreme price volatility, mean we must reduce our dependence on cobalt.

“While it remains the most effective material to combat wear in dry running valve seat applications and other components subjected to big temperature ranges, we have used our extensive experience in powder metallurgy to develop a low-cobalt sintered formulation alternative that delivers similar wear properties to the best current materials.”

Research began by selecting two proven sintered products: FM-8100, an iron-based cobalt-free sintered material; and FM-T95A, a cobalt-based sintered material. A series of tests were then conducted by the business using a total of five materials, the two mentioned above containing the lowest and highest cobalt contents.

Based on results and an investigation of worn specimens, it was found the cobalt-containing Tenneco sintered material formed a wear-reducing tribolayer at lower temperatures than a cobalt-free one. After meeting production and quality requirements, the new material – made up of sintered steel with only a 17% cobalt content­ – was developed and named FM-T88A.

Collaborative trials then took place with a global vehicle manufacturer to compare wear resistance of the new material against series production materials in a test rig containing a turbocharger wastegate bushing running at temperatures around 800°C (1,472°F).

Olivetti concluded, “The results showed that at 200°C, FM-T88A displays a significantly reduced depth of wear compared with a cobalt-free material and is at a comparable level of wear resistance to the high-cobalt material. At all other temperatures the new material’s performance closely mirrored the high-cobalt materials.”

Mahle has developed a new laser welding production process, enabling a kidney-shaped cross section of the piston gallery. The greater design freedom for the piston gallery therefore enables the use of steel pistons in diesel engines.

Thick walls have poor heat dissipation and produce high temperatures at the bowl rim, while thin walls can lead to undesired high temperatures at the inner wall of the piston gallery, causing a layer of oil carbon to form. This layer of oil carbon acts as a thermal insulator and promotes due to excessive operating temperatures undesired wear and damage to the piston and cylinder liner.

The ability to produce a kidney-shaped cross section guides the cooling oil flow in an optimal hydraulic path and ensures uniform heat dissipation that prevents overheating.

While it is typical to use friction welding to produce pistons, the material buildup in the cooling channel hinders the controlled guidance of the cooling oil flow.

The use of steel pistons in passenger car diesel engines saves fuel and thus significantly reduces CO₂ emissions. The lower expansion levels of steel compared to aluminum has a positive effect on frictional losses.

Steel pistons can also have a shorter top land and allow for a longer connecting rod with their low overall height. The smaller pivoting angle of the longer connecting rod results in smaller lateral forces and lower friction in the region of the piston skirt.

Zircotec Group has developed the first plasma-applied thermal barrier coating that can be used with composites requiring a Class A display surface.

The new technology allows vehicle manufacturers to use the lightweight material in places that have previously not been possible, such as aerodynamic aids near exhaust pipes or the exhaust shrouds themselves.

The technology was developed from Zircotec’s proven plasma-applied ceramic coating at the company’s in-house R&D facility; the chemistry of the compound and the application process have been significantly modified specifically for application to composite materials.

The automotive industry is increasingly adopting composite components, largely to meet strict emissions regulations but also due to consumer demand for the aesthetic qualities of the materials. However, using composites close to heat sources has previously required some form of heat shielding, which adds components and is largely rejected by vehicle manufacturers which are looking to maintain the aesthetics of visible surfaces.

With new manufacturing techniques starting to make carbon composites more affordable, the material is increasingly offering an ideal solution where high strength must be combined with light weight.

Zircotec’s proprietary application process requires specialized equipment and highly trained technicians. The coating has been extensively trialled with a number of Europe’s most demanding vehicle manufacturers and is now available for wider application.

Monitor Coatings Ltd, a surface engineering specialist from the UK, has announced that following investment from Innovate UK, the company is working in collaboration with Cranfield University. The project will conduct a series of studies that aim to develop low cost customisable coatings, which can coat 3D geometries whilst protecting against aggressive high temperature environments.

The study, which started in September 2017, will use the process of exothermic reaction synthesis to modify low cost sprayed metallic surface coatings. The need to reduce CO2 emissions is pushing thermal power plants to use higher operating temperatures and biomass/waste derived fuels, increasing the demand on heat exchanger tubes. The ‘ER-Sealcoat’ project aims to develop a low cost method of producing customisable coatings that can coat 3D geometries (internal and external) and protect against aggressive high temperature environments.

The seal coating is produced as a tailored slurry mix containing chemically active components, which react exothermically with the sprayed base coat. The heat released from this stored chemical energy enhances diffusion and intermetallic formation with the basecoat, producing a sealed surface with a bespoke chemical gradient capable of resisting fireside corrosion and high temperature oxidation in aggressive conditions such as biomass/waste fired advanced thermal power plant.

The ER-Sealcoat system would result in improved performance through its functional gradient design and ability to close surface breaking porosity and seal the coating, as a result reducing direct and indirect processing costs compared to current industrial coating methods. With a growing portfolio of products and a comprehensive range of services, Monitor Coatings continue to invest in Research and Development to ensure technology enhancement and quality is at the forefront of the organisation.

“I’m delighted that Innovate UK have been able to support this exciting project, and help our organisation to turn strategic plans into reality,” explained Dr Spyros Kamnis, research and development manager of Monitor Coatings. “The Industrial Strategy Challenge Fund aims to bring together the UK’s world leading research with business to meet the major industrial and societal challenges of our time. Monitor Coatings Ltd have ongoing, long-lasting collaboration with Cranfield University with outstanding return on productivity and performance

by utilising the funds being available in a quality way.”