HiSiaddi is an innovative foreign trade service provider driven by dual engines of technology commercialization and foreign trade services. It has established a "1+2+3+4=1" service system and can supply silicon nitride powder from multiple well-known original manufacturers.
As an R&D-focused new-type foreign trade trader, HiSiaddi has repeatedly proposed formula optimization schemes and application improvement suggestions for silicon nitride powder by leveraging technological cooperation with factories and precise insight into market demands. Below is a consulting case of HiSiaddi on silicon nitride powder formula optimization.
Please contact HiSiaddi customer service if you need more formula optimization consulting services.
CeramPower SAS of France is located in the high-tech material industrial park of Lyon. It is a leading European manufacturer of new energy vehicle IGBT power modules and AMB copper-clad silicon nitride substrates, with mass supply of power electronic control components for Valeo, Schneider and local European vehicle manufacturers. Its products fully comply with EU automotive standards AEC-Q102, RoHS and REACH control regulations. For over a decade, the company has stably purchased high-purity silicon nitride powder from Ube Industries, Japan, with an annual silicon nitride demand of 138 tons for rigorous mid-to-high-end vehicle-grade raw materials. Its formula has been filed with the French National Institute of Materials, and major raw material ratios and sintering additive systems are regulated by laws, prohibiting large-scale modification of basic formulas.
Amid extended international shipping cycles, three consecutive price hikes by Japanese original manufacturers and delivery lead times stretched to 90 days, the customer selected mass-produced high-purity silicon nitride from a leading domestic Chinese manufacturer after preliminary sample screening. The first batch of 65 tons of domestic powder arrived for production, aiming to cut production costs by 32% via imported raw material substitution. However, after official launch on tape casting + atmospheric sintering production lines, three fatal mass production defects emerged within only 15 days: agglomeration and caking of tape casting slurry, massive scrapping of green bodies with uneven thickness, large-area internal pores and penetrating edge cracks on sintered finished substrates. The finished products failed to meet automotive factory standards for thermal conductivity and bending strength. The scrap rate surged from 0.7% with Japanese powder to 27.3%, forcing a 50% capacity reduction on two core AMB substrate production lines. Delivery deadlines for downstream Valeo orders loomed, and unresolved failures in the short term would expose the enterprise to heavy default compensation.
The domestic silicon nitride supplier could only guarantee physical and chemical indicators of factory powder and issue COA quality inspection forms per national standards. Its R&D team focused solely on powder synthesis and production, lacking technical reserves for downstream tape casting forming and ceramic sintering end applications. It could only slightly adjust powder oxygen content and particle size, unable to implement systematic rectification combined with the customer’s slurry formula and workshop production processes. The customer’s material engineers were familiar with matching logic for European local raw materials but lacked understanding of microcrystalline phases, surface oxide layers and impurity distribution characteristics of domestic silicon nitride. Multiple independent adjustments to binder and sintering additive proportions worsened defects. The customer fully entrusted HiSiaddi’s technical service team to station on-site and systematically identify root causes of failures from four dimensions: powder traceability, slurry formula optimization, workshop production process rectification and fine-tuning of customized powder, and deliver full-chain technical solutions.
Original technical requirements of the customer: Without altering the core basic formula (fixed powder solid content and total addition of basic sintering additives), rely on fine powder adjustment + refined auxiliary ratio optimization + production process improvement to reduce the product scrap rate below 2% and realize stable mass substitution of Japanese imported silicon nitride with domestic powder.
Collaborating with a CNAS-certified third-party testing laboratory, HiSiaddi collected samples of stock domestic silicon nitride raw powder, defective slurry on-site, scrapped green bodies and cracked sintered substrates for full testing including XRD crystal phase analysis, oxygen-nitrogen analysis, ICP impurity detection, SEM micromorphology observation and particle size distribution measurement. Combined with full-process production records of workshop temperature and humidity, ball milling, tape casting, degreasing and sintering, three categories of root causes were identified originating from micro-defects of powder itself, mismatched slurry auxiliary ratios and poor adaptation of customer production process parameters, with failure causes analyzed item by item:
The measured total oxygen content of domestic silicon nitride powder was 1.18 wt% (vs. 0.85 wt% for Japanese imported powder). A dense SiO₂ oxide film formed on the powder surface with far higher polarity than silicon nitride bulk, resulting in poor compatibility with the customer’s existing oil-based PVB binder system. Meanwhile, loose control over powder classification introduced abundant free submicron ultra-fine powder, whose sharply increased specific surface area prevented full powder coating under the fixed dispersant dosage. Rapid agglomeration and flocculation occurred during ball milling and stirring, causing local caking and slurry stratification. After tape casting, green body thickness difference exceeded 0.12 mm with dense edge material shortage and pinholes, accounting for over 35% of single-batch green body scrap. The customer previously fixed dispersant dosage at 0.65% referencing Japanese powder, failing to account for the high oxygen and high specific surface area characteristics of domestic powder, leading to severe insufficient dispersant addition as the direct formula-level trigger.
The customer’s process required raw α-Si₃N₄ to be controlled within 90%~93%, while the delivered domestic powder measured only 85.2% α-phase with elevated β-phase content. Rapid α-to-β crystal phase transformation during sintering created significant differences in local volume shrinkage coefficients, generating massive internal stress inside substrates and forming radial penetrating cracks at edges and centers of large-size substrates after cooling. Additionally, total K and Na alkali metal impurities in the powder reached 2.8 ppm (vs. below 1 ppm for Japanese raw materials). Alkali metals formed low-melting silicate glass phases during 1750 ℃ high-temperature sintering, locally melting and aggregating to form closed internal pores, dropping finished substrate thermal conductivity from the target 82 W/(m·K) to 57 W/(m·K) and failing to meet mandatory heat dissipation indicators for automotive IGBTs. The customer’s original Y₂O₃-Al₂O₃ sintering additive ratio was designed for low-impurity Japanese powder, and abnormal reactions between trace impurities and additives generated heterophases that further amplified pore defects.
Domestic silicon nitride powder adsorbed trace organic residual impurities. When combined with the customer’s original binder system, the original uniform heating rate of 3 ℃/min during low-temperature degreasing decomposed binders violently in a short time, and internal gas inside green bodies could not be slowly discharged to form microbubbles, which ruptured and extended into cracks during subsequent high-temperature sintering. Meanwhile, the workshop batching area maintained a constant humidity of 62%, and domestic powder absorbed moisture faster than imported powder. Moisture adsorbed after opening was introduced into slurry, and residual carbon concentrated at grain boundaries during degreasing, further increasing substrate failure probability.
HiSiaddi adopted a two-step rectification logic: first optimize on-site formulas and production processes to temporarily reduce scrap rates, then reverse push upstream powder factories to fine-tune powder processes for long-term stable supply. The core constraint of the customer was fully observed throughout: no major changes to the base substrate formula and total sintering additive dosage, only refined fine-tuning optimization.
1. Gradual fine-tuning of dispersant: Without altering total powder addition, dispersant dosage was raised from the fixed 0.65% to 0.82%, adopting low-acid-value phosphate ester dispersants to preferentially coat the surface SiO₂ oxide layer of powder and reduce powder polarity differences to eliminate slurry agglomeration. Plasticizer dosage was simultaneously adjusted down from 7.2% to 6.5% to balance slurry rheological properties and prevent flowing defects from excessively low viscosity.
2. Implementation of new pre-mixing pretreatment process: A powder pre-dispersion step was added, where silicon nitride powder was pre-stirred with partial solvent and a small amount of dispersant for 2 hours to fully infiltrate powder surfaces before feeding into the main ball mill tank, avoiding instant agglomeration of ultra-fine powder. Ball milling duration was extended from 12 h to 15 h to ensure uniform powder dispersion in the organic system.
3. Local fine-tuning of sintering additives: While maintaining total additive dosage at 8%, the ratio of Y₂O₃ to Al₂O₃ was adjusted from 6:2 to 6.5:1.5 to inhibit generation of low-melting heterophases by alkali metal impurities and reduce formation of closed sintering pores, matching the trace impurity characteristics of domestic powder.
1. Upgrade environmental control of tape casting workshop: Dehumidification equipment was installed in batching and ball milling workshops to stabilize ambient humidity at 42%~48%. All silicon nitride powder must be fed within 24 hours after opening, and remaining powder stored under vacuum sealing to isolate moisture adsorption and oxidation from air.
2. Redesigned segmented heating curve for degreasing furnaces: The original uniform heating mode was abandoned in favor of three-stage stepped degreasing: slow heating at 1 ℃/min from room temperature to 220 ℃, 2 h holding at 220~450 ℃ to fully decompose binders, uniform heating at 2 ℃/min from 450 to 600 ℃, paired with trace nitrogen-hydrogen mixed protective atmosphere to slowly discharge decomposed gas inside green bodies and eliminate residual carbon and blister defects.
3. Optimized segmented sintering temperature control: The 1750 ℃ sintering holding time was shortened from 4 h to 3.2 h to match the α-β phase transformation rate of domestic powder, relieve concentrated shrinkage stress and reduce crack generation via process adjustments.
HiSiaddi coordinated upstream silicon nitride manufacturers to lock exclusive production lines for targeted optimization of synthesis and post-processing processes, customizing improved powder matching the customer’s vehicle-grade requirements:
1. Optimization of segmented temperature control in nitriding furnaces: Adjust the heating curve for direct silicon powder nitriding to precisely stabilize α-phase content within the compliant range of 91.2%~92.5% and strictly control β-phase proportion. Adopt high-purity nitrogen plus trace hydrogen deoxidation process to reduce total powder oxygen to 0.87 wt%, matching oxygen levels of Japanese raw materials.
2. Acid washing + multi-stage full ceramic-lined classification: Finished powder was soaked in high-purity dilute acid for impurity removal to eliminate soluble alkali metal impurities on the surface, reducing total K+Na to 0.78 ppm. Full ceramic-lined jet milling + three-stage precision jet classification screened out excessive free ultra-fine powder, stably controlling D50 at 0.9 μm with particle size span D90/D10 ＜2.7 to narrow powder particle size range and improve slurry dispersion stability.
3. Low-temperature surface passivation modification of powder: Finished powder underwent low-temperature gas-phase passivation treatment to form an extremely thin uniform passivation layer on the powder surface, weakening polarity of surface SiO₂ and significantly improving compatibility with the customer’s PVB organic system, eliminating slurry agglomeration risks from the powder source.
HiSiaddi customized exclusive incoming acceptance standards for the customer: every batch of domestic silicon nitride must undergo four mandatory inspections before delivery: XRD crystal phase analysis, oxygen-nitrogen content testing, full ICP impurity detection and particle size measurement. Unqualified powder was prohibited from production. Meanwhile, fixed silicon powder grades, production teams and process parameters were locked for upstream factories to eliminate batch-to-batch indicator drift during mass production.
1. On-site small trial rectification (implemented in 7 days): Relying on temporary formula and process optimization, the existing 65 tons of stock powder were adjusted for production. On the third day of production, green body scrap rate dropped from 35% to 4.1%, sintering crack defects decreased by 70%, and overall finished product scrap rate fell to 5.3%. The customer temporarily eliminated the risk of order suspension and secured delivery deadlines for current Valeo orders.
2. Verification of improved customized powder pilot trials (500 kg samples): Optimized customized silicon nitride was airfreighted to the French factory for pilot production, with the optimized formula and production processes applied throughout. Tape casting green bodies featured uniform thickness without pinholes, sintered substrates had no penetrating cracks and internal porosity below 0.3%. Finished product thermal conductivity reached 83.5 W/(m·K) with three-point bending strength of 795 MPa, all performance indicators exceeding the factory standards of the customer’s Japanese raw materials. The scrap rate dropped to 1.12%, meeting vehicle factory delivery standards.
3. Finalization of full-year bulk signing: The customer formally confirmed a full-year 138-ton annual procurement order delivered in 7 quarterly batches, including 122 tons of standard mass-produced customized powder and 16 tons of modified silicon nitride dedicated to new high-thermal-conductivity substrate R&D. HiSiaddi coordinated overall upstream production scheduling, factory quality inspection, export customs clearance and supporting EU compliance documents. The comprehensive procurement cost of localized raw materials dropped by 31.8% compared with original Japanese powder, and ocean shipping lead time was shortened from 90 days to 36 days. The customer’s AMB substrate domestic localization yield stabilized above 98.7% post-project, achieving steady production cost reductions for three consecutive quarters.
1. Summary of existing industry pain points: Most domestic silicon nitride powder manufacturers focus on mass production of general sintering and wear-resistant ceramic grades with fixed production processes, only controlling products per national physical and chemical standards. They lack R&D teams for end tape casting forming and high-temperature sintering applications. Minor differences in domestic powder crystal phase ranges, surface oxygen content and trace impurity control logic compared with Japanese imported powder trigger full-chain mass production defects in slurry and sintering once applied to European mid-to-high-end vehicle ceramic enterprises whose formulas are filed with national material institutions and prohibit large-scale modification of base formulas. Powder suppliers only deliver goods without capacity to assist downstream end-users in formula adaptation and production process optimization, which constitutes the core barrier to overseas market penetration of high-end domestic powder.
2. Core service value of HiSiaddi: Breaking the traditional foreign trade model of simple commodity sales, HiSiaddi forms a full-chain technical closed loop: defect detection and tracing of defective products → powder defect localization → fine-tuning of end formulas → on-site production process rectification → reverse customized technical renovation of upstream powder → construction of long-term incoming quality control systems. It bridges the gap in end application technical capabilities of domestic powder factories and compensates for information gaps of overseas high-end customers regarding performance characteristics of domestic powder, breaking technical barriers for overseas landing of high-end domestic powder via implementable full-cycle technical services.
3. Extension of long-term customer business: Following successful project delivery, the French enterprise fully entrusted HiSiaddi with exclusive agency of all China sourcing, customized development, formula technical matching and export compliance services for three core raw materials of automotive heat dissipation ceramics: high-purity aluminum nitride, submicron silicon carbide and special boride powder. Leveraging this silicon nitride mass production failure troubleshooting case, HiSiaddi subsequently developed two leading European new energy ceramic substrate end clients in Spain and Belgium, continuously expanding its foreign trade business territory for mid-to-high-end advanced powder raw materials in Europe.
Please contact HiSiaddi customer service for more formula optimization consulting services.
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