Warm Spray Deposition Low Porosity Coating 2026
Warm Spray Deposition Low Porosity Coatings
Warm spray deposition achieves dense, low-porosity coatings by controlling particle temperature below the feedstock melting point while accelerating particles to supersonic velocities. This report maps core mechanisms, application domains, and assignee activity across retrieved patent and literature records.
Warm Spray: Tunable Kinetic Deposition for Dense Coatings
Warm spray deposition occupies a strategically important niche between fully molten thermal spray and fully solid-state cold spray. By controlling particle temperature and velocity to remain below the feedstock melting point while significantly above ambient, the process enables dense, low-porosity coatings with minimized oxidation and phase degradation — properties increasingly demanded in aerospace, energy, and wear-protection applications.
The process is distinguished by three core technical capabilities: reduced critical velocity requirement due to thermal softening of particles, suppressed oxidation compared to fully molten spray processes, and tunable microstructures ranging from porous to near-fully dense by independently controlling particle temperature and velocity. These principles were formalized in the foundational 2008 study on warm spraying as a novel coating process based on high-velocity impact of solid particles.
Within the broader low-porosity coating space, overlapping technical families include high-velocity cold spray variants, HVAF/HVOF combustion-driven cermet coating systems, low-pressure and very low pressure plasma spray (VLPPS), and suspension or liquid feedstock plasma spray for nano- and submicron powder delivery. Each approach targets dense coating formation through different mechanisms of particle heating and acceleration.
The innovation timeline spans a foundational period from 2006 to 2011, a development and benchmarking phase from 2013 to 2018, and an industrial scaling period from 2019 to 2023. In this dataset, the National Research Council of Canada holds the highest multi-jurisdictional filing volume in retrieved records, while Fujimi Incorporated and Sulzer Metco represent key industrial specialty players.
Filing Trends and Technology Cluster Distribution
Retrieved records span 2006 to 2025 across multiple spray technology clusters. Filing and publication activity shows a clear progression from foundational process patents to industrial-scale application and emerging suspension and laser-assisted hybrid approaches.
Patent Records by Technology Cluster — Low Porosity Coatings (Dataset Snapshot)
In this dataset, cold spray and HVOF/HVAF cermet coating clusters account for the largest share of retrieved records, reflecting their established industrial adoption relative to warm spray-specific filings.
↗ Click bars to explorePatent Filing Activity by Period — Warm Spray & Low Porosity Coatings (Dataset Snapshot)
In this dataset, filing and publication activity accelerated markedly in the 2019–2023 industrial scaling period, reflecting growing adoption of cold spray and HVAF as commercial-grade low-porosity deposition processes.
↗ Click bars to exploreKey Application Areas for Warm Spray and Low Porosity Coating Technology
Retrieved records identify four primary application domains where warm spray, cold spray, HVOF, and suspension plasma spray are deployed for low-porosity coating formation: aerospace gas turbines, industrial wear and corrosion protection, nuclear and energy systems, and electronics sputtering target manufacturing.
Aerospace Gas Turbine TBC Systems
Thermal barrier coatings for turbine hot-section components represent the highest-value application in this dataset. Mitsubishi Heavy Industries Aero Engines’ 2025 pending US patent specifies HVOF suspension spray with topcoat temperatures held at 300–450°C and unmelted ceramic agglomerate area fraction ≤0.15%. VLPPS coatings in the 1–100 µm range achieve PVD-comparable quality at deposition rates an order of magnitude higher, as documented in the 2011 review.
AerospaceIndustrial Wear and Corrosion Protection
WC-Co(Cr) cermet coatings deposited by HVOF, HVAF, warm spray, and cold spray are extensively documented for wear-resistant surface protection in hydraulic cylinders, pump bores, and automotive valve components. HVOF-ID spraying with WC-CoCr (−15+5 µm) powder uses statistical design-of-experiments optimization to produce internal diameter coatings competitive with OD HVOF standards, as reported in the 2019 study. Low-pressure cold-sprayed WC-17Ni coatings achieve minimum porosity at optimal gas temperatures of 500°C.
Industrial MachineryNuclear Reactor Vessel Heat Transfer
Cold spray microporous coatings applied to reactor vessel outer surfaces are demonstrated to enhance critical heat flux (CHF) under simulated in-vessel retention conditions, as reported in the 2017 study on downward-facing saturated boiling heat transfer. This represents a niche but strategically significant nuclear safety application where coating porosity architecture is deliberately engineered rather than minimized. The technique uses cold spray process conditions to control micropore geometry for boiling enhancement.
Nuclear EnergyElectronics Sputtering Target Manufacturing
Cold spray deposition of Sn+In2O3 transparent conductive oxide cermet coatings directly onto copper backing plates bypasses conventional sintering and bonding steps, reducing sputtering target manufacturing cost, as documented in the 2017 microscopic examination study. This application leverages the solid-state nature of cold spray to preserve the cermet phase composition of the TCO material. The approach is applicable to large-area sputtering target production for display and photovoltaic industries.
Electronics ManufacturingKey Patent Assignees in Warm Spray & Low Porosity Coatings (Retrieved Records)
In this dataset, National Research Council of Canada holds the highest filing count with 5 patent records across WO, CA, EP, and US jurisdictions. Fujimi Incorporated accounts for 4 records in retrieved records, focused on thermal spray slurry formulations for dense ceramic coatings.
Top Assignees by Filing Count — Warm Spray & Low Porosity Coatings (Dataset Snapshot)
↗ Click bars to exploreNational Research Council of Canada
National Research Council of Canada holds 5 patent records in this dataset spanning WO (2017), CA (2017), EP (2019), US (2021), and US (2022) jurisdictions, all directed to ShockWave Induced Spraying (SWIS) for controlled-porosity metal coatings. An additional EP pending application covers a temperature-controlled cold spray apparatus using in-situ laser heating and remote temperature sensor feedback for additive manufacturing predictability. Active grants in US (2021, 2022) make this the broadest multi-jurisdictional SWIS portfolio in retrieved records.
CanadaFujimi Incorporated
Fujimi Incorporated holds 4 patent records in this dataset across US (2016 active, 2017 active, 2021 active) and EP (2017 inactive) jurisdictions, covering thermal spray slurry formulations for dense ceramic coating formation. The slurry patents specify ceramic particle suspensions with viscosity ≤3,000 mPa·s and average particle size from 1 nm to 5 µm, enabling fine-structured dense coatings. This patent family targets applications requiring controlled nano- and submicron powder delivery not achievable with conventional powder feed systems.
JapanFrontier Technologies in Low Porosity Spray Deposition (2022–2026)
Based on the most recent filings and publications in this dataset (2022–2026), five emerging directions are identifiable: suspension HVOF for dense TBCs, temperature-feedback cold spray for additive manufacturing, MAX phase cold spray coatings, ultra-dense glass-ceramic cold spray, and hybrid powder-suspension and laser-assisted processes.
Suspension HVOF for Sub-0.15% Unmelted Fraction TBCs
Mitsubishi Heavy Industries Aero Engines’ 2025 pending US patent specifies high-velocity flame spray of ceramic powder suspension at controlled topcoat temperatures of 300–450°C, targeting an unmelted ceramic agglomerate area fraction of ≤0.15% in the deposited thermal barrier coating layer. This approach is functionally equivalent to warm spray temperature control logic applied to ceramic feedstocks, and R&D teams should monitor this convergence for freedom-to-operate implications. It represents the leading-edge filing in this dataset for dense TBC formation via liquid feedstock delivery.
Temperature-Feedback Cold Spray for Additive Manufacturing
National Research Council of Canada’s EP pending application (2021) describes an apparatus using in-situ laser heating and remote temperature sensor feedback to control cold spray deposition conditions for additive manufacturing predictability. This moves cold spray beyond surface coating into precision near-net-shape manufacturing for aerospace alloy components including Ti, Al, and Ni superalloys. The temperature control approach converges cold spray behavior toward warm spray conditions by thermally softening particles prior to impact, analogous to the effect documented for 316L stainless steel at nitrogen propellant gas temperatures of 700–800°C.
Warm Spray vs. Cold Spray: Key Technical Dimensions
Click any row to explore further.
| Dimension | Warm Spray | Cold Spray |
|---|---|---|
| Particle Temperature | Below feedstock melting point; thermally softened state | Well below melting point; ambient to ~1000°C propellant gas for high-pressure systems |
| Particle Velocity | Supersonic; independently tunable from temperature | Supersonic; 730–855 m/s documented for Ti6Al4V; up to 5 MPa / 1000°C in advanced guns |
| Minimum Porosity Achieved | Near-fully dense; competitive with HVOF for WC-12Co in ID spray (fine powder −10+2 µm) | 1.6% for Ti6Al4V at 855 m/s; non-connected micron-sized gradient porosity for stainless steel confirmed by 3D X-ray microtomography |
| Oxidation Suppression | High — sub-melting particle state suppresses oxide formation relative to HVOF/plasma | Highest — fully solid-state deposition; oxide-free bond coats (NiCoCrAlY) validated as alternatives to LPPS/VPS |
| Key Materials | WC-12Co cermet (ID spray), oxide crystal coatings, aggregate particles with K-value particle size formulation | Ti6Al4V, 316L stainless steel, WC-17Ni, NiCoCrAlYHfSi, Sn+In2O3 cermet, MAX phase (Ti3AlC2, Ti2AlC) |
| Primary Applications | Dense cermet and oxide coatings; confined geometry (ID) spray; carbide and intermetallic coatings requiring oxidation suppression | Aerospace structural repair, additive manufacturing, sputtering targets, nuclear CHF enhancement, bond coats, wear protection |
| Patent Landscape (Dataset) | National Institute for Materials Science (2010, US) is primary warm-spray-specific anchor; sparse recent warm-spray-specific cluster — identified as strategic white space | National Research Council of Canada (5 records, SWIS, WO/CA/EP/US); Plasma Giken USA Corp. (EP 2014); multiple Chinese filers in 2025 |
| Process Pressure | Combustion or mixed-gas stream; specific pressures not detailed in retrieved records | Up to 5 MPa in advanced cold spray guns (Plasma Giken USA Corp., EP 2014) |
Frequently Asked Questions: Warm Spray Deposition & Low Porosity Coatings
Warm spray deposition controls particle temperature to remain below the feedstock melting point while accelerating particles to supersonic velocities. This gives three key properties compared to cold spray and HVOF: reduced critical velocity requirement due to thermal softening, suppressed oxidation compared to fully molten spray, and tunable microstructures by independently controlling particle temperature and velocity. Cold spray operates at fully solid state, while HVOF involves fully or partially molten particles.
For Ti6Al4V, porosity drops from approximately 11% to 1.6% as particle velocity increases from 730 to 855 m/s using N2-He mixed propellant gas. For stainless steel coatings, 3D X-ray microtomography confirms non-connected, micron-sized gradient porosity structures. Low-pressure cold-sprayed WC-17Ni coatings achieve minimum porosity at optimal gas temperatures of 500°C. Beijing Tianli Chuang’s 2025 CN pending glass-ceramic cold spray patent claims ≤0.1% porosity after sintering.
In this dataset, National Research Council of Canada holds the highest multi-jurisdictional filing volume with 5 patent records across WO (2017), CA (2017), EP (2019), US (2021), and US (2022) jurisdictions, all directed to ShockWave Induced Spraying (SWIS) for controlled-porosity metal coatings, plus an additional EP pending application on temperature-controlled cold spray for additive manufacturing.
Suspension HVOF uses liquid feedstock delivery to inject nano- or submicron ceramic powder suspensions into a high-velocity flame spray system. Mitsubishi Heavy Industries Aero Engines’ 2025 pending US patent specifies topcoat temperatures of 300–450°C and unmelted ceramic agglomerate area fraction ≤0.15%, controlling particle thermal state during deposition — a principle functionally equivalent to warm spray temperature control logic applied to ceramic feedstocks. Fujimi Incorporated’s slurry patents cover suspensions with viscosity ≤3,000 mPa·s and particle size 1 nm–5 µm.
Retrieved records identify four primary domains: aerospace gas turbines (thermal barrier coatings for turbine hot-section components using VLPPS, suspension plasma spray, and HVOF-suspension systems); industrial wear and corrosion protection (WC-Co(Cr) cermet coatings for hydraulic cylinders, pump bores, and valve components); nuclear and energy systems (cold spray microporous coatings on reactor vessels to enhance critical heat flux); and electronics sputtering target manufacturing (cold spray Sn+In2O3 TCO cermet coatings directly onto copper backing plates).
Based on the most recent records in this dataset, emerging materials include MAX phase compounds (Ti3AlC2, Ti2AlC) cold-sprayed to avoid oxidation and phase decomposition; glass-ceramic powder systems achieving ≤0.1% porosity with coefficient of thermal expansion 70–100 × 10⁻⁷/°C; NiCoCrAlYHfSi bond coats deposited by laser-assisted cold spray (LACS) for high-temperature applications; and hexagonal boron nitride solid lubricant incorporated into Cr3C2-NiCr cermet matrices via suspension HVAF injection.
Data and insights on this page are based on a limited patent and literature dataset and are for reference only. Figures may not represent the complete technology landscape.