# README — Laser Diffraction Particle Size Distribution Data

## General Remark ##
This dataset is associated with the following publication "Particle size analysis and beyond - laser diffraction and derived information regarding structures of mechano-fusion coated particles" and contains particle size distribution (PSD) data measured by laser diffraction. Furthermore, this data is closely related to another publication "Guest Particle Deformation and Powder Flow Behavior in Mechano-Fusion: Linking Microscopic Structure to Macroscopic Performance" and its raw data, which is archived under: https://doi.org/10.25532/OPARA-933.

**Particle size analysis and beyond - laser diffraction and derived information regarding structures of mechano-fusion coated particles**

Abstract:
*Laser diffraction (LD) is widely used for the analysis of particle size distribution (PSD). Due to the structure of dry-coated mechano-fusion particle systems, the interpretation of the PSD remains challenging. This study investigates hetero-aggregate coating structures of alumina host particles (median diameter 43.3 μm) with polystyrene guest particles (mean diameter 3.5 μm) in dry LD measurements and how dispersion conditions influence the PSD. Gentle freefall dispersion preserves coating structures and yields a monomodal PSD consistent with expected coated particle size. Differences in the PSD between samples of coated particles prepared under different process conditions are only observed using highintensity dry dispersion. High-intensity dispersion alters the aggregation state by detaching guest particles, leading to bimodal PSD. The plateau values in the cumulative distribution furthermore exceed theoretical guest volume fractions. Experimental measurements are combined with simulations of diffraction patterns and inverse reconstruction. Simulations qualitatively support the experimental findings by linking particle arrangement and deformation to reconstructed PSD features. The apparent overrepresentation is attributed to guest particle deformation and comminution, biasing the volume-weighted PSD. Hence, LD provides more than particle size information: aggregation state, dispersion-induced changes, and guest particle deformation are revealed, enhancing the applicability of LD for quality control of dry-coated hetero-aggregates.*

Authors: 
Judith Miriam Seyffer, Rahul Mitra, Urs Alexander Peuker
Technische Universität Bergakademie Freiberg  
Institute of Mechanical Process Engineering and Mineral Processing  
Agricolastraße 1  
D-09599 Freiberg  
Germany

## Laser diffraction equipment ##

All LD measurements were peformed using the **Helos/KF (Sympatec GmbH, Clausthal, Germany)** in dry disperion. High-intensity dry dispersion uses the **Helos Rodos** module at different pressure settings. Gentle, freefall dispersion is acchieved with the **Helos Gradis** module. The Helos features a helium-neon laser (632.8nm) and a detector with 31 elements. The measurements are performed in ambient air with lens R3 (0.5/0.9...175 μm). The device software (Windox 5.8.2.0) offers implementations of either Fraunhofer or Mie theory as an optical model to process the raw data for obtaining a PSD as part of the so-called High Resolution Laser Diffraction (HRLD).

## Sample material and sample preparation ##

Representative samples for LD measurements were produced by sample splitting using the **rotary micro riffler (QuantaChrome Instruments, Boynton Beach, USA)**. Three different types of sample were investigated:

- **Pristine materials** 
    - Host particle type: Alumina (DAW-45, Denka Chemcial GmbH, Düsseldorf Germany) - median diameter d50=43.3 μm according to manufacturer, spherical particle shape: https://www.denka.co.jp/eng/product/detail_00040/
    - Guest particle type: Polystyrene (PS; SX350-H, Soken Chemical & Engineering Co., Ltd., Tokyo, Japan; acquired through Kowa Europe GmbH, Düsseldorf, Germany) - monodisperse, mean diameter d=3.5 μm according to manufacturer, spherical particle shape: https://www.sokenchem.com/en/product/fine_particles/sx/

- **Feed**
    - Unprocessed mixture of alumina and PS according to guest particle weight ratio xwt,guest=9.81% (corresponds to guest particle volume ratio xvol,guest=27.42%) before mechano-fusion

- **Mechano-fusion coated particle samples**
    - All coated particles were produced by mechano-fusion using the Angmill Mechano-Fusion system (AMS) of the **Hosokawa Picobond** module connected to the **machinery platform Picoline (Hosokawa Alpine AG, Augsburg, Germany)**
    - For the three rotational speeds 4000 / 5000 / 6000 1/min, three different process times were chosen 15 / 30 / 45 min. Therefore, nine process parameter combinations were chosen and three experimental campaigns were performed. LD measurements were performed for on at least two samples from different experimental campaigns for one process parameter combination.

At least two LD measurements were performed for each sample.

## Dataset overview ##

All LD measurements of PSD are combined in one Excel file "Laser_diffraction_data.xlsx". A CSV file "Laser_diffraction_data.csv" with the exact same content is provided in case Microsoft Excel is not available. 

One individual measurement consists of multiple rows, where each row represents one particle size value `x_µm` and the corresponding cumulative PSD value `Q3_percent`. Further columns provide all relevant metadata of the LD measurement and the mechano-fusion process parameters for all coated particle samples.

For example, a single measurement of the pristine alumina sample contains 32 rows with different `x_µm` values in the range from 0.5...175µm and `Q3_percent` values in the range from 0...100%. To reconstruct or plot one complete PSD curve, the data must be filtered and grouped by the relevant metadata, to be introduced in more detail in the following.

## Structure of the data and column description

**`Column name` | Description | [Selectable parameters for filtering]**

- `x_µm` | Particle size value. The unit is µm. | []
- `Q3_percent` | Cumulative volume-based particle size distribution value. Values given in %. | []

A complete PSD measurement is obtained by grouping rows that share the same measurement-identifying metadata, typically:

- `Sample` | Name of the measured sample | [Alumina / PS / Feed / *XXX*]  --> *XXX* represents the sample number of the mechano-fusion experiment. This identifier must be used when referencing further data of the experiments, e.g. mechano-fusion process data, which is archived here: https://doi.org/10.25532/OPARA-933 
- `Measurement` | LD measurement replicate identifier. This column helps distinguish repeated measurements of the same sample under otherwise identical conditions. | [1 / 2 / 3 / 4]
- `Optical_model` |  Optical model used for the LD evaluation in the software. | [Fraunhofer / Mie]
- `Refractive_index` | Refractive index used for the LD evaluation in the software. The value `n.a.` indicates that no refractive index was specified when using the Fraunhofer optical model. | [1.59 / 1.77 / n.a.]
- `Dispersion_type` | Dispersion system (device configuration) used during dry LD measurements. | [Helos_Rodos / Helos_Gradis]
- `Dispersion_pressure_bar` | Dispersion pressure used during the Helos_Rodos measurement, given in bar. The value `n.a.` indicates that no pressure setting is selected for measurements of Helos_Gradis. | [0.5 / 1.0 / 2.0 / n.a.]

And any mechano-fusion (MF) parameters, if applicable:

- `MF_Rotational_speed_1/min` | Rotational speed used during mechano-fusion processing, given in 1/min. For pristine materials and the feed, this value is set to `0`. | [0 / 4000 / 5000 / 6000]
- `MF_Process_time_min` | Mechano-fusion process time, given in minutes. For pristine materials and the feed, this value is set to `0`.  | [0 / 15 / 30 / 45]
- `MF_param` | Combined mechano-fusion parameter label with rotational speed followed by process time. For pristine materials and the feed, this contains the sample name and 0, indicating the reference or untreated state. | [e.g. `Alumina/0`, `6000/30`]
- `MF_Experimental_campaign` | Identifier of the mechano-fusion experimental campaign. For pristine materials and the feed, this value is set to `0`. | [0 / 1 / 2 / 3]

## Recommended filtering

Before plotting, comparing, or statistically evaluating the data, users should filter the dataset to select the desired measurement or set of comparable measurements. Filtering by the LD measurement parameters is important because laser diffraction results can depend on the optical model, refractive index settings, dispersion type, and dispersion pressure. Measurements should only be directly compared when the relevant measurement settings are identical or when differences in settings are intentionally part of the analysis.