Как проверить и найти поставщиков карбида кремния в Китае: руководство по аудиту для технических закупщиков

Verification of a China SiC vendor includes production capacity audit, test certificate validation, and batch consistency procedures. Authentic suppliers have their own milling systems, laser diffraction size analyzer, and trace impurity specifications in addition to general quality statements.

Step 1: Distinguishing SiC Manufacturers from Trading Companies

• The key factor in separating a true SiC manufacturer from a trading company is having control over crushing, shaping and screening operations versus office presentations only.
• Plant Processing Equipment: True processing facilities use Raymond Mills, Jet Mills for micropowder, ultrasonic vibrating sieves and acid/water wash equipment.
• Traceable Testing Facilities: QA facilities need to have a laser particle size analyzer (Malvern Mastersizer) and carbon/sulfur analyzer.
• Company Business Scope: Check the business scope of the company. SiC manufacturers say “processing and manufacturing” whereas pure traders will say “sales” or “trade”.

Step 2: Interpreting the Silicon Carbide COA

Scientifically sound COA should contain concrete figures regarding the boundaries of particular elements as per the globally accepted standards (FEPA, JIS, or ANSI).Core Criterion: Do not approve a COA which says “High Purity ≥98.5%”. COA should contain the precise upper limits of Free Carbon (F.C.), Magnetic Iron (Fe3O4/Fe2O3), and Free Silicon (F.Si).Standard Chemical Specification Thresholds for Premium Grade SiC

Step 3: The Reasons for Mismatch Between Approved Pre-shipment Samples and Bulk Shipments (Prevention Procedures)

Disparities arise due to irregular lump grading, lack of air classifier calibration, or screen mesh blinding after prolonged operations.Particle Size Distribution (PSD) Change: The small change in the D97 particle size and coarse particles can scratch the surface in abrasive and wire saw grinding.Secondary Feedstock Blending: The low-cost feedstocks contain secondary re-melted SiC, resulting in varied thermal and hardness characteristics.

Buyer Preventive Measures

1.Demand Matching Heat Batch Run Number on All Bags: This must be present on all 25 kg bags and 1-ton jumbo bags.

2.Require Retention Samples: Demand contractually that the seller maintains 1 kg of sealed batch retention samples for a minimum of 12 months from the dispatched lot.

3.Require PSD Specifications Other Than Nominal Mesh: Set limits for D3, D50 and D94, in accordance with JIS R6001/FEPA standard 42-1:2006.

Step 4: Silicon Carbide Procurement from Manufacturers Checklist

1.Prior to issuing the official Purchase Order (PO) and/or setting the payment terms, make sure the following commercial specifications have been met:

2.Grain Size Standard: Specify whether the grain size standard used is FEPA “F” for bonded abrasives, FEPA “P” for coated abrasives or other such as JIS/ANSI standards.

3.Packaging: 25kg multi-wall valve paper bags in UV stabilized 1,000kg woven big bags on fumigated or composite pallets.

4.Third Party Pre-Shipment Inspection: Include provision allowing the buyer to conduct container stuffing inspection through SGS or CCIC at the place of shipment.