Ci a ion: F anke, J.; Kou ecký, T.;
Kou ný, D. Compa ison o
Sublima ion 3D Scanning Sp ays in
Te ms o Thei E ec on he Resul ing
3D Scan, Thickness, and Sublima ion
Time. Ma e ials 2023,16, 6165.
h ps://doi.o g/10.3390/
ma16186165
Academic Edi o : Tao Wang
Recei ed: 3 Augus 2023
Re ised: 8 Sep embe 2023
Accep ed: 8 Sep embe 2023
Published: 11 Sep embe 2023
Copy igh : © 2023 by he au ho s.
Licensee MDPI, Basel, Swi ze land.
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ma e ials
A icle
Compa ison o Sublima ion 3D Scanning Sp ays in Te ms o
Thei E ec on he Resul ing 3D Scan, Thickness, and
Sublima ion Time
Jakub F anke, Tomáš Kou ecký* and Daniel Kou ný
Ins i u e o Machine and Indus ial Design, Facul y o Mechanical Enginee ing, B no Uni e si y o Technology,
Technická2896/2, 616 69 B no, Czech Republic; [email p o ec ed] (J.F.); [email p o ec ed] (D.K.)
*Co espondence: [email p o ec ed]
Abs ac :
This s udy compa ed eigh sublima ion scanning sp ays in e ms o hei e ec on 3D scan-
ning esul s, coa ing hickness, and sublima ion ime. The wo k used an au oma ed sp aying sys em
o ensu e he same deposi ion condi ions o all es ed ma e ials. All expe imen s we e pe o med
unde he same en i onmen al condi ions o exclude he in luence o he ambien en i onmen on
he coa ings. All es ed scanning sp ays c ea ed coa ings wi h hicknesses in he o de o ens o
mic ome e s ha we e de ec able by he 3D scanne A os III T iple Scan. The coa ings mus be
applied ca e ully when accu a e measu emen s a e equi ed. All used ma e ials enabled he cap u e
o he highly e lec i e su ace o he Si-wa e . Howe e , he di e ences be ween some sp ays we e
signi ican . Sublima ion ime measu emen s showed ha all coa ings disappea ed om he Si-wa e
su ace comple ely. Ne e heless, all coa ings le isible aces on he mi o -like su ace. They we e
easily wiped o wi h a clo h.
Keywo ds:
op ical 3D scanning; ma e coa ing; scanning sp ay; sublima ion coa ing; coa ing hickness
1. In oduc ion
Op ical 3D scanne s a e used in a wide ange o applica ions o hei abili y o
digi ize physical objec s in o he i ual en i onmen . They a e ypically used o e e se
enginee ing, geome ic and dimensional inspec ion, medical pu poses, e c. This wo k
ocused on ac i e op ical iangula ion-based 3D scanne s, speci ically s uc u ed ligh
scanne s. The wo king p inciple o hese scanne s is desc ibed in he wo k o Sansoni [
1
].
The scanne consis s o a p ojec o and came a/s. The p ojec o p ojec s a ligh pa e n on
he scanned objec , which is de o med by he objec geome y, and he came as cap u e
he scene. The o ien a ion and posi ion o he p ojec o and came as in he scanne body
a e known hanks o he calib a ion. I enables he econs uc ion o he scanned objec s
by iangula ion.
The ad an ages o s uc u ed ligh scanne s a e hei scanning speed and he ac
ha hey a e non-con ac . Howe e , hey ha e limi a ions when objec s wi h p oblema ic
su aces mus be scanned, ypically specula ( e lec i e), anslucen , anspa en , o da k
su aces [
2
]. I is coupled wi h he wo king p inciple o hese scanne s when he p ojec ed
ligh is e lec ed om he scanned objec . A p ope e lec ion om he scanned su ace
is hus essen ial. Phenomena coupled wi h he scanning o he specula su ace we e
desc ibed in he wo k o Wang and Feng [
3
]. In his case, he mos p oblema ic is a specula
e lec ion. In he wo k o Chen [
4
], he e ec o he anslucen su ace on he esul s o
s uc u ed ligh 3D scanning was discussed. P ojec ed ligh can pene a e he anslucen
su ace, esul ing in he w ong compu a ion o a dep h coo dina e o he scanned poin
cloud, which can lead o a non-accu a e 3D scan. In he case o anspa en su aces,
con en ional scanne s ail comple ely. The p oblem wi h da k su aces is ha hey abso b
he p ojec ed ligh and hus educe he amoun o e lec ed ligh in o he came as o he
Ma e ials 2023,16, 6165. h ps://doi.o g/10.3390/ma16186165 h ps://www.mdpi.com/jou nal/ma e ials
Ma e ials 2023,16, 6165 2 o 15
scanne . The in luence o he scanned su ace colo on he esul s o 3D scanning was
in es iga ed in he wo k o Zaimo i´c-Uzuno i´c and Lemeš [
5
]. All p oblema ic su aces
gene ally lead o 3D scans wi h e o s o scans wi h insu icien in o ma ion abou he
digi ized su ace.
The e a e wo app oaches o digi izing p oblema ic objec s using he 3D scanne .
The i s one is based on using special 3D scanning echniques. The main d awback
o his app oach is ha each ype o p oblema ic su ace equi es a di e en scanning
echnique wi h speci ic ha dwa e and so wa e. This is epo ed in he wo k o Ih ke [
6
].
The second app oach is based on using a empo a y ma e coa ing. In his case, he scanned
su ace is co e ed by a ma e coa ing, which imp o es i s op ical p ope ies and enables i s
digi iza ion. The main ad an age o his app oach is ha i is usable o all con en ional
3D scanne s. The disad an age o his app oach is ha he applied coa ing can change
he geome y o he scanned objec because i is an added ma e ial on he su ace o he
scanned body, as was s a ed in he wo k o Rukosuye [
7
]. Fo accu a e 3D scanning, he
coa ing hickness mus be as hin as possible and a he same ime mus su icien ly imp o e
he op ical p ope ies o he scanned su ace. The opic o he ine e en coa ing was also
he scope o he wo k o Maeng and Lee [
8
]. They explo ed he usabili y o elec os a ic
powde coa ing o 3D scanning pu poses. In his s udy, bo h coa ing and emo al p ocess
we e in es iga ed.
The wo k o Paloušek [
9
] was ocused on he e ec o ma e coa ing on he accu acy o
op ical 3D scanning. A chalk sp ay and i anium dioxide (TiO
2
) deposi ed by an ai b ush
gun we e used as he coa ing ma e ials. The coa ing hickness o he chalk sp ay was
a ound 44
µ
m, while he i anium-based coa ing was almos en imes hinne . The coa ing
hickness alues we e ob ained based on he 3D scanning o he coa ed gauges. Ano he
pape dealing wi h TiO
2
-based coa ings and hei e ec on 3D scanning accu acy is he wo k
o F anke [
10
]. This wo k was ocused on op imizing he p ocess o ma e coa ing deposi ion
in e ms o coa ing hickness and ma ing abili y. The esul ing coa ings had a hickness
below 1
µ
m and p o ided su icien op ical p ope ies o accu a e 3D scanning. The coa ing
hickness in his s udy was measu ed by s ylus p o ilome e . The wo k o Pe ei a [
2
] is
ano he s udy ocusing on he e ec o he coa ing ma e ial on 3D scanning accu acy. The
gold, sil e , pla inum, and ca bon deposi ed by spu e ing we e used as coa ing ma e ials.
All hese ma e ials we e sui able o accu a e 3D scanning and measu emen s wi h a
ole ance o up o 0.01 mm, compa ed o he adi ionally used de elope . The e ec o
he ma e coa ing on he 3D scanning accu acy in den al applica ions was discussed in he
wo k o Bu de [
11
]. Ae osol sp ays, such as Helling 3D Lase Scanning An i-Gla e and
Digiscan-Sp ay, we e used as ma ing agen s. Bo h sp ays had accep able coa ing hickness
o clinical use. The coa ing hickness was a ound 16.1
µ
m o he Helling sp ay and
13.6
µ
m o he Digiscan sp ay. The coa ing hickness alues we e ob ained by compa ing
he 3D scans o he non-coa ed and coa ed pa . The wo k o Yang [
12
] s udied he e ec
o he chalk sp ay coa ing on he 3D scanning esul s. In his case, he e ec s o sp ay
condi ion and sp ay ope a o skills on he p ecision o 3D scanning we e in es iga ed.
F om he na u e o he p e iously men ioned coa ing ma e ials, he e is one mo e
disad an age o ma e coa ings. Cleaning mus be pe o med o emo e he coa ing om
he su ace o he scanned objec . The cleaning is gene ally conduc ed by wiping wi h
a clo h o wi h a b ush o by washing. Some imes, an ul asonic cleane mus be used.
Howe e , in some cases, e en an ul asonic cleane canno comple ely emo e he coa ing
ma e ial om he su ace. This is ypical o TiO
2
-based coa ings and hei applica ion on
ubbe su aces, ough su aces, su aces wi h complex geome y, e c. This disad an age
can be elimina ed by using sublima ion scanning sp ays, which spon aneously anish
om he scanned su ace a e 3D scanning. Sublima ion coa ings we e in es iga ed in
he wo k o Díaz-Ma ín [
13
]. In his case, cyclododecane was used as a coa ing agen
o he 3D scanning o a chaeological objec s. The sublima ion a e measu emen in his
s udy was based on he scanning p ocess. The e ec i e ime in which cyclododecane
can be used as an opaci ie o acquisi ion pu poses was es ima ed. Nowadays, he e a e
Ma e ials 2023,16, 6165 3 o 15
sublima ion ma e ials de eloped especially o 3D scanning on he ma ke , which a e lis ed
as ollows: Aesub (Scanningsp ay Ve iebs GmbH, Recklinghausen, Ge many), Re lecon
Type 1 (MR Chemie GmbH, Unna, Ge many), and A blime (G aichen P oduk ions- und
Ve iebs GmbH, Bensheim, Ge many) [
14
–
16
]. Cu en ly, he only in o ma ion abou hese
ma e ials is s a ed in he da ashee s p o ided by hei manu ac u e s, i.e., cu en ly, he e is
a knowledge gap in he in es iga ion and e i ica ion o hei p ope ies in e ms o ma ing
e iciency, hickness, o sublima ion ime.
The main goal o his wo k is a compa ison o a wide ange o comme cially a ailable
sublima ion scanning sp ays. This wo k e i ied he e ec o he numbe o applied coa ing
laye s on he 3D scanning esul s and coa ing hickness. This s udy also in es iga ed
he o e all one-laye coa ing sublima ion ime. The wo k conside ed cons an condi-
ions o all expe imen s and coa ing deposi ion o maximize objec i i y when compa ing
indi idual ma e ials.
2. Ma e ials and Me hods
Scanning sp ays used in his wo k a e s a ed in Table 1. Cu en ly a ailable comme cial
sp ays ha we e dedica ed as sublima ion scanning sp ays we e used o he pu pose o
his wo k. The abb e ia ions s a ed in Table 1a e used u he in his wo k o a dis inc ion
o he sp ays. All es ed ma e ials we e deli e ed as ae osol sp ay cans. In he igh column,
sublima ion imes decla ed by he manu ac u e s o he scanning sp ays a e also men ioned.
The sp ays Re T50, A AB6, A AB2, and A AB0 a e cyclododecane-based, while he o he
sp ays a e based on o he ma e ials. The exac composi ion o he p oduc s is no speci ied
by he manu ac u e s.
Table 1. Lis o used sublima ion scanning sp ays.
Manu ac u e Sp ay Type Abb e ia ion Sublima ion
Time (min)
Scanningsp ay
Ve iebs GmbH
Aesub Blue AbB 240
Aesub O ange AbO 720–1440
MR Chemie GmbH
Re lecon Ta nish 11-HC Re T11 60–180
Re lecon Ta nish 12-HC Re T12 60–120
Re lecon Ta nish 50 Re T50 300–480
G aichen P oduk ions-
und Ve iebs GmbH
A blime AB6 A AB6 360–600
A blime AB2 A AB2 120–240
A blime AB Ze o A AB0 60–120
An au oma ed coa ing deposi ion sys em was used o ensu e uni o m condi ions o
coa ing applica ion (see Figu e 1).
Sp ay mo emen was ensu ed by a s eppe mo o wi h a bel d i e and linea guiding.
Coa ing deposi ion om he sp ay can was u ned on using a se o mo o wi h a igge
placed on he op o he sp ay holde (see Figu e 1). The igge in ensi y was se he
same o all used scanning sp ays. Sp ay mo emen speed, numbe o deposi ed coa ing
laye s, and igge ing o he sp ay we e d i en by a mic ocon olle A duino placed in
he con ol panel. The sp ay mo emen speed was se a a cons an 800 mm/s o all
pe o med expe imen s. The sp ay axial dis ance was also se as cons an , and all coa ings
we e deposi ed a a dis ance o 175 mm om he sp ay nozzle. The sp ay mo emen speed
and deposi ion dis ance we e se expe imen ally o a oid o e -sp aying a e one sp ay
pass. Coa ing deposi ion was conduc ed pe pendicula ly o he coa ed su aces, and he
sp ay axis was di ec ed a he cen e o he sample. Fou samples we e c ea ed o each
measu emen . All expe imen s we e pe o med unde cons an ambien condi ions. The
ambien empe a u e o all expe imen s was 21
±
1
◦
C. All expe imen s we e pe o med
2 min a e he coa ing deposi ion o elimina e he e ec o he ambien en i onmen and
he ime-dependen beha io o he coa ings.
Ma e ials 2023,16, 6165 4 o 15
Figu e 1. Coa ing deposi ion sys em.
2.1. Coa ed Objec s
A highly e lec i e Si-wa e (15
×
15
×
0.5 mm) was used o he su ace co e age
analysis, he analysis o he ma ing e iciency, and he measu emen o he sublima ion
ime. The Si-wa e was chosen o i s excellen la ness (<400 nm) and low oughness
(Ra ≈1 nm)
. The la ness and oughness o he Si-wa e we e measu ed by he s ylus
p o ile B uke Dek akXT (B uke , Bille ica, MA, USA), wi h a s ylus adius o 12.5
µ
m, a
s ylus o ce o 3 mg, and a scan du a ion o 160 s. The su ace o he Si-wa e is impossible o
scan wi hou a ma e coa ing, which was necessa y o ma ing e iciency analysis. Excellen
la ness and low oughness we e necessa y o de e mine he e ec o ma e coa ing on he
3D scan quali y.
A whi e ce amic gauge block wi h a nominal dimension o 30 mm (30
×
35
×
9 mm)
was used o he measu emen o he coa ing hickness. I was used because i s su ace is
possible o scan wi hou ma e coa ing and o i s p ecise geome y.
Objec s used o he coa ing deposi ion we e no p e ea ed be o e he ma ing p o-
cess. Wiping wi h he clo h was pe o med be o e es ing o emo e he dus and o he
impu i ies om he es su ace. This co esponds o a common wo k low du ing he
3D scanning p ocess.
2.2. 3D Scanning
A os III T iple Scan (Ca l Zeiss GOM Me ology GmbH, B aunschweig, Ge many)
was used o 3D scanning. The 3D scanne was used o he e i ica ion o he e ec o
he coa ing on he 3D scan quali y and he coa ing hickness measu emen . The p ocess o
3D scanning was au oma ed using an assembly wi h he li and o a ion able o ensu e
uni o m condi ions du ing measu emen s, and each sample was scanned in one sho .
Scanning de ails a e men ioned in Table 2. A 3D scanning se up di e ed o he Si-wa e
and ce amic gauge block measu emen .
Ma e ials 2023,16, 6165 5 o 15
Table 2. The 3D scanning de ails.
Gene al Pa ame e s
Senso ATOS III Re . 02
Came a esolu ion 2 ×8 Mpx
P ojec o ligh Blue
P ojec ion S uc u ed ligh wi h phase shi
3D scanning se up
Scanned objec Si-wa e Gauge block
Measu ing olume MV60 MV170
Came a posi ion SO SO
Measu ing olume
dimensions (60 ×45 ×35) mm (170 ×130 ×130) mm
Measu ing poin dis ance 0.017 mm 0.055 mm
Measu ing dis ance 490 mm 490 mm
Exposu e ime 50 ms 35 and 70 ms
Ce i ica e VDI/VDE 2634
Pa 3
•P obing e o o m
(sigma) 0.001 mm 0.001 mm
•P obing e o (size) 0.002 mm −0.005 mm
•Sphe e spacing e o −0.001 mm 0.002 mm
Au oma ed scanning Li and o a ion able
Scanning o ien a ion 0◦45◦
Polygoniza ion and
pos -p ocessing S anda d
2.2.1. 3D Scanning o he Si-Wa e
The Si-wa e was scanned by a measu ing olume MV60, wi h pe pendicula scanning
o ien a ion be ween he scanne and wa e . MV60 o e ed he bes possible measu ing
poin dis ance. Pe pendicula o ien a ion o e ed he wo s scanning scena io when he
ligh was e lec ed di ec ly on he came as o he scanne . This measu emen was made o
in es iga e he e ec o ma e coa ing on he 3D scan quali y and i s abili y o imp o e he
3D scanning o he highly e lec i e su ace. The analysis o he 3D scans was pe o med in
he so wa e GOM Inspec (Ca l Zeiss GOM Me ology GmbH, B aunschweig, Ge many).
The coa ing abili y o imp o e 3D scanning was e alua ed by measu ing he a ea cap u ed
by he scanne and he numbe o holes in he scanned mesh. The size o he e alua ed a ea
was 12
×
12 mm. The 3D scan quali y was e alua ed by he s anda d de ia ion (Sigma) o
he cap u ed poin cloud agains he i ed plane. The i ed plane was c ea ed using he
Gaussian Bes - i me hod, wi h a selec ion o poin s in he ange o 3σ.
2.2.2. 3D Scanning o he Ce amic Gauge Block
The gauge block was scanned by measu ing olume MV170 due o i s la ge dimen-
sions. In his case, he scanning o ien a ion was se as 45
◦
o elimina e p oblema ic di ec
e lec ions du ing 3D scanning. This measu emen was conduc ed o in es iga e he coa ing
hickness. The use o 3D scanne o he coa ing hickness measu emen was mo i a ed
by he ollowing s a emen s: Fi s ly, 3D scanning esul s can show he e ec o he coa ing
on he 3D scanning accu acy, i.e., 3D scanning esul s can show i he coa ing is de ec able
by he scanne . Secondly, he 3D scanne can cap u e he en i e coa ed su ace in one sho .
I was necessa y o elimina e he ime-dependen beha io o deposi ed coa ings. The
gauge block was coa ed in he middle o he su ace, de ining i s nominal dimension (see
Figu e 2). The wid h o he coa ed a ea was 15 mm. The es o he su ace emained

Ma e ials 2023,16, 6165 6 o 15
uncoa ed, which de ined a ze o e e ence plane. This was achie ed using a clamping mask
du ing he coa ing deposi ion.
Figu e 2. Scheme o he coa ing deposi ion on he gauge block.
The coa ing hickness was measu ed in he so wa e GOM Inspec . The dis ance
be ween he coa ed a ea and he ze o e e ence plane was measu ed using he P ojec ed
Poin Dis ance unc ion. The measu emen was conduc ed o 9 measu ing poin s. The i s
measu ing poin was in he cen e o he coa ed a ea. The es o he measu ing poin s we e
o se om he cen e poin by
±
1.5 mm in he Ydi ec ion and by
±
5 mm in he Zdi ec ion.
2.3. Co e age o he Si-Wa e by he Coa ing
The analysis o he co e age o he Si-wa e by he coa ing was pe o med o de e mine
he amoun o deposi ed coa ing ma e ial. Coa ings we e cap u ed by an op ical mic oscope
Olympus SZX7 (Olympus, Tokyo, Japan). Magni ica ion was se as 1. The pe cen age
o e lap o he wa e su ace by he coa ing was measu ed in he so wa e ImageJ, Ve sion
1.53 (NIH, Be hesda, MD, USA and LOCI, Uni e si y o Wisconsin-Madison, Madison,
WI, USA) using he Measu e unc ion. Fo his analysis, cap u ed images we e con e ed
in o a bina y image by h esholding (see Figu e 3). Whi e spo s in Figu e 3 ep esen he
coa ing. The h esholding was also pe o med in he ImageJ so wa e, Ve sion 1.53 , whe e
he h eshold was se using he Yen algo i hm [17].
Figu e 3. Con e sion o he cap u ed image in o he bina y image.
Ma e ials 2023,16, 6165 7 o 15
2.4. Sublima ion Time Measu emen
The sublima ion ime measu emen was pe o med in he closed box
(180 ×120 ×130 mm)
, which elimina ed he e ec o he ambien en i onmen . Subli-
ma ion ime was measu ed based on he images aken by he came a Imaging Sou ce
DMK 23U618 (The Imaging Sou ce, LLC, Cha lo e, NC, USA) wi h he lens Compu a
T0812FICS-3 (CBC G oup, Tokyo, Japan). Samples we e pho og aphed e e y 60 s, and he
sublima ion ime was compu ed om he ime s amps o he aken pho os. Measu emen s
we e au oma ed using Py hon sc ip and mic ocon olle A duino. The sublima ion ime
ep esen s he momen when he coa ing comple ely disappea ed om he su ace o he
Si-wa e a e i s deposi ion.
3. Resul s and Discussion
3.1. Co e age o he Si-Wa e by he Coa ing
The g aphs in Figu e 4show he a e age co e age o he Si-wa e depending on he
numbe o applied coa ing laye s. The esul s show ha he co e age abili y di e ed
be ween indi idual sp ays. I was he mos ob ious in he case o he one-laye coa ing.
The highes co e age abili y was p o ided by sp ays Re T11 and Re T50, which eached he
co e ages o 97.9
±
0.8% and 99.2
±
0.2% wi h only he one-laye coa ing. On he con a y,
he lowes a e age co e age wi h he one-laye coa ing was p o ided by he sp ay AbB
(63.8 ±2.7%).
Figu e 4.
Dependence o he co e age o he Si-wa e by he coa ing on he numbe o applied
coa ing laye s.
I was assumed ha he co e age abili y could be coupled no only wi h he com-
posi ion o he sp ayed ma e ial bu also wi h he olume ic low a e o he ma e ial in
he c ea ed sp ay. The sp ay cans we e weigh ed by he digi al balance Jade e JKH-500
(Jade e Scale Co., L d., New Taipei Ci y, Taiwan) be o e and a e he coa ing deposi ion o
ack he loss o he ma e ial. The weigh losses o he ma e ial in he sp ay cans a e he
one sp ay c ossing o e he coa ed objec (i.e., a e deposi ion o he one-laye coa ing) a e
s a ed in Table 3. I is ob ious ha he sp ay AbB p o ided he lowes weigh loss, which
was p obably e lec ed in i s lowe co e age abili y wi h he one-laye coa ing. I was also
obse ed ha he sp ays Re T12, A AB6, A AB2, and A AB0, despi e hei ela i ely high
weigh losses, p o ided less co e age abili y wi h hei one-laye coa ings. These one-laye
coa ings we e isually less homogeneous and con ained mo e impe ec ions compa ed o
he coa ings deposi ed by he sp ays Re T11, Re T50, and AbO.
Table 3. The loss o ma e ial in he sp ay can a e he deposi ion p ocess o he one-laye coa ing.
Sp ay Loss o Ma e ial (g)
AbB 0.77 ±0.16
AbO 0.98 ±0.10
Re T11 1.54 ±0.21
Re T12 1.45 ±0.17
Re T50 1.41 ±0.17
A AB6 1.32 ±0.24
A AB2 1.39 ±0.12
A AB0 1.72 ±0.23
Ma e ials 2023,16, 6165 8 o 15
The esul s in Figu e 4also show ha he ou -laye coa ing led o co e age g ea e
han 95% o almos all used scanning sp ays. F om Figu e 4, i is also clea ha he
sp ays AbB, A AB2, and A AB0 did no each such co e age a highe numbe s o laye s
compa ed o o he es ed ma e ials. This was coupled wi h impe ec ions in he coa ings.
In his case, la ge holes and c acks we e mo e equen ly p esen in he mo phology o he
coa ings (see Figu e 5). A hypo hesis explaining he c ack o ma ion in hese coa ings was
se . I was assumed ha he c acks we e o med by sol en ha is p esen in he sp ays.
I he e is a la ge amoun o he sol en deli e ed on he coa ed su ace, i dis up s he
s uc u e o he coa ing ha is al eady p esen on he su ace, leading o he c ea ion o he
coa ing impe ec ions. Figu e 5shows images o he ou -laye coa ings deposi ed on he
Si-wa e . De ails o he coa ings a e shown in he ed squa es. I is ob ious ha he coa ing
mo phology di e ed o each sp ay.
Figu e 5. Images o he 4-laye coa ings.
3.2. 3D Scanning
The coa ing quali y was coupled wi h he esul s o 3D scanning. Lack o co e age led
o incomple e 3D scans wi h low quali y. The esul s o 3D scanning a e summa ized in he
g aphs shown in Figu es 6and 7. Figu e 6shows a dependency o he scanned a ea (SA)
and he numbe o holes (H) in he cap u ed mesh on he numbe o applied coa ing laye s.
The maximal scanned a ea was 144 mm
2
, which was de ined by he selec ed con ol a ea
12 ×12 mm.
Figu e 6.
The dependence o he scanned a ea and numbe o holes in he scanned mesh on he
numbe o applied coa ing laye s.
Figu e 7.
The dependency o he scanned poin cloud Sigma on he numbe o applied coa ing laye s.
Ma e ials 2023,16, 6165 9 o 15
The esul s o he 3D scan quali y analysis a e shown in Figu e 7. He e, he s anda d
de ia ion (Sigma) o he scanned poin cloud in dependency on he numbe o applied
coa ing laye s is s a ed. The g aphs show he a e age alues.
F om he 3D scanning esul s, i is clea ha mos o he sp ays showed simila ends
in hei beha io . The inc easing numbe o applied coa ing laye s inc eased he co e age
o he wa e (see Figu e 4), leading o he scanning o he whole con ol a ea wi h a educed
numbe o holes (see Figu e 6). The esul s in Figu e 7also ha e simila ends o mos o
he used sp ays. The Sigma ends gene ally consis o he down end, he minimum, and
he up end. An explana ion o each pa o he Sigma end is p o ided by he ollowing
hypo hesis. The dec easing end o he Sigma was coupled wi h he elimina ion o he
p oblema ic e lec ions o he ligh om he mi o -like su ace o he Si-wa e by he
coa ing. The inc easing end o he Sigma alue was hen coupled wi h a mic os uc u e
o he coa ing, which can be mo e no iceable wi h mo e coa ing laye s. The minimum o
he g aph indica es he coa ing wi h he bes pa ame e s om he 3D scan quali y poin o
iew. Al hough he esul s had simila ends o mos o he used sp ays, he nume ical
esul s di e ed.
Coa ings applied by he sp ays Re T11 and Re T50 enabled he scanning o he whole
su ace wi hou holes s a ing wi h he one-laye coa ing. The ends in Figu e 6a e o he
sp ays Re T11 and Re T50 and a e mo e o less he same. The esul s in Figu e 7show ha
coa ings deposi ed om hese sp ays can be sensi i e o o e -sp aying (see he inc easing
Sigma alue). The sp ays A AB6 and AbB we e also sensi i e o o e -sp aying (see Figu e 7).
The sp ay A AB6 p o ided he bes scan quali y wi h he wo-laye coa ing, whe e he Sigma
alue was a i s minimum. Mo e coa ing laye s esul ed in conside able deg ada ion o he
3D scan quali y in luenced by he ough mic os uc u e o he coa ing. On he o he hand,
mo e laye s elimina ed he holes in he mesh. AbB had he bes scanning esul s wi h he
ou -laye coa ing. In his case, mo e coa ing laye s (o e -sp aying) led o ex ensi e c acks
in he coa ing mo phology, esul ing in a educed scanned a ea and inc eased numbe o
holes in he mesh (see Figu e 6). I also nega i ely a ec ed he 3D scan quali y (see he
inc easing Sigma alue in Figu e 7). The ou -laye coa ing also wo ked well in he case o
he sp ay Re T12. The con ol a ea was cap u ed comple ely, holes we e elimina ed, and
he Sigma alue was a i s minimum. The sp ay AbO p o ided he bes scanning esul s
wi h a highe numbe o coa ing laye s. The six-laye AbO coa ing p o ided he scans
wi h he bes quali y o all es ed sp ays. Th ee-dimensional scans wi h low Sigma alues
we e also o e ed by he sp ay A AB0. Howe e , A AB0 coa ings con ained impe ec ions
ha nega i ely a ec ed he cap u ed scans, which con ained holes. The wo s scanning
esul s we e om he sp ay A AB2. E en he six-laye coa ing was no su icien o cap u e
he con ol a ea comple ely. Th ee-dimensional scans con ained a la ge numbe o holes,
and he Sigma alues we e he highes o all used sp ays. I is clea om Figu e 5 ha
he A AB2 coa ing mo phology appea ed di e en compa ed o he o he ma e ials. In
his case, he coa ings consis ed o small needle-like clus e s, which p obably had a lowe
abili y o elimina e he p oblema ic e lec ions du ing 3D scanning. I was assumed ha
such a beha io was coupled wi h he composi ion o he scanning sp ay A AB2.
3.3. Coa ing Thickness
The esul s o he coa ing hickness measu emen a e shown in Figu e 8. The g aphs
show he a e age alues and s anda d de ia ions (black lines). Figu e 8shows ha all
used sp ays c ea ed coa ings wi h conside able hicknesses de ec able by he scanne . This
sugges s ha all es ed scanning sp ays mus be used ca e ully because hicknesses in
he ange o ens o mic ome e s can in luence he accu acy o 3D scanning. The coa ing
hickness in he ange o ens o mic ome e s was also ypical in he s udies o Paloušek
and Bu de [
9
,
11
], whe e he non-sublima ion scanning sp ays we e in es iga ed. I is wo h
saying ha when he maximum possible scanning accu acy is equi ed, TiO
2
-based coa ings
a e s ill he mos sui able. Acco ding o he wo k o F anke [
10
], TiO
2
-based coa ings can
be deposi ed wi h hicknesses lowe han 1 µm.